TL;DR: A retractable security gate, also called a trellis, trelli, or concertina gate, is a sliding steel or aluminium barrier that locks across an opening, and folds away when you don’t need it. The names all mean the same thing, but what sets gates apart is the build: the steel, the uprights, the locks, the bolts and the fitting. DEFENDoor custom-builds four models and measures your opening for free.
A retractable security gate is a sliding, expanding steel or aluminium barrier that locks across a doorway or patio and folds away when it isn’t needed. South Africans also call it a trellis gate, trelli gate, or concertina gate.
Housebreaking is the crime South African households are most likely to face, and a security gate is the barrier most people fit first. The trouble is that almost every retractable gate looks the same in a photo. Two gates can sit side by side, priced hundreds of rands apart, and you’d struggle to tell the difference by eye. The most important design features are always under the finish, including the steel gauge, the locks, the bolts, and the way the gate is anchored to your wall. Those are the things you can’t see once the job is done, and they’re exactly the things that decide whether a gate protects your family. This guide walks you through what to look at before you buy, so you’re comparing gates properly and not just comparing photographs.
What Is a Retractable Security Gate?
A retractable security gate is a concertina-style steel or aluminium barrier that slides along a track and expands across an opening when you need protection. When it’s open, it stacks neatly to one side. When it’s closed, it forms a locked physical barrier over a door, window, patio, or shopfront.
Unlike a fixed burglar gate, a retractable one gives you security without permanently blocking the opening.
That flexibility is why you’ll find retractable gates on all sorts of openings:
- Front, patio, sliding, and stacking doors
- Shopfronts and office entrances
- Passages and internal doorways
- Homes, flats, and estate houses
- Schools, retail stores, and warehouses
If your priority is keeping patio and sliding doors open for airflow, our guide to patio and sliding-door security gates covers that use case in detail.
You’ll also hear the same product called by several names. They all describe the same thing:
| Term | Meaning |
|---|---|
| Retractable security gate | The industry product category |
| Retractable gate | A shortened version |
| Trellis gate | Common South African term |
| Trelli gate | A popular spelling variation |
| Sliding security gate | Describes the sliding action |
| Concertina gate | Describes the folding mechanism |
Trellis, Trelli, Retractable, or Sliding: Is There a Difference?
For South African buyers, “trellis gate”, “trelli gate”, “retractable gate”, “sliding gate” and “concertina gate” all describe the same product: a sliding, expanding security barrier. The name changes from supplier to supplier, but the gate doesn’t.
So the useful question isn’t what a gate is called. It’s how it’s made and how it’s fitted. A cheap gate and a well-built one can carry the exact same name and look almost identical in a brochure. The next few sections show you where they actually differ.
Steel or Aluminium: Which Retractable Gate Is Right for You?
Steel is always the stronger choice for security and suits high-risk homes and commercial sites. Aluminium is lighter and naturally rust-resistant, and some people consider them for coastal properties.
Steel, however, is the clear winner as it gives you rigidity and impact resistance, which is why it stays the default where security is the priority. It’s also ideal for larger openings and stands up to the daily wear a busy entrance puts on a gate.
| Feature | Steel | Aluminium |
|---|---|---|
| Security strength | Excellent | Good |
| Impact resistance | Excellent | Moderate |
| Large openings | Excellent | Good |
| Commercial use | Excellent | Good |
| Corrosion resistance | Good with the right finish | Excellent |
| Coastal suitability | Good with the right finish* | Excellent |
| Rigidity | Excellent | Good |
| Weight | Heavier | Lighter |
| Maintenance | Low | Low |
DEFENDoor builds security gates in steel, with a powder-coated, weather-resistant finish for exceptional rust protection. For most South African security jobs, steel is still the choice where structural strength matters most.
*The suitability of steel in coastal environments depends on the protective finish, specification, and maintenance requirements.
What Makes One Retractable Gate Stronger Than Another?
A retractable gate’s strength comes down to eight things, most of them invisible once it’s fitted:
- The uprights. These are the vertical bars that give the gate its frame. DEFENDoor uses one continuous steel bar per upright rather than two thinner bars joined along their length. Gates with that join have a weak point, because it gives a crowbar a seam to work into and lever apart. A single bar leaves nothing to prise. Our higher models use 19mm steel uprights, against the 10mm-12mm commonly used elsewhere, and seven to nine millimetres sounds trivial until something is levered against it.
- The top track. This guides and carries the moving gate, and DEFENDoor makes it from steel. A steel track keeps the gate aligned and running true for years, where a thin or badly fitted track distorts and wears out early. It also resists the classic attack of levering the track open to pull the bars out.
- The bearings. The gate rolls on sealed steel bearings locked into that track with steel bolts. They come pre-lubricated and sealed, so there’s no greasing or oiling to keep up with. Cheaper gates sometimes run on plastic wheels, which wear and crack over time.
- The locks. A gate is only as good as its lock. DEFENDoor fits high-security star-key hook locks, which resist the picking and snapping that defeat an ordinary cylinder first. The higher models carry two separate locks, so forcing one achieves nothing on its own.
- The flights. The folding lattice is made of flights, the diamond-cross sections that let the gate expand and contract. DEFENDoor locks its flights into the bars rather than leaving them loose, so the lattice behaves as one structure under load instead of a set of hinged parts. The flagship DX-222 adds two sets of 5mm high-security zig-zag flights on top of its standard diamond crosses, for an extra layer of bracing.
- The rivets. These hold the moving sections together and take the strain every time the gate opens and closes. DEFENDoor uses stainless steel rivets on the DX-310, DX-420, and DX-222, and SABS-approved aluminium rivets on the DX-215. Stainless steel resists the corrosion that undoes cheaper rivets.
- The bottom bolts. The bolts that lock into the bottom track are solid steel encased in glass-filled nylon on the DX-310, DX-420, and DX-222. The steel does the security work, and the nylon lets the bolt spin quietly, which makes it very hard to hacksaw, because a blade can’t bite on something that keeps turning away from it. The DX-215 uses spinning nylon-6 bolts that lock into the track the same way.
- The anchoring. Your gate won’t hold if it isn’t secured properly to the wall. With building standards being what they are, the wall is often the weak point, and criminals lever gates straight out of their frames. DEFENDoor’s patented Anchor Brace system locks the top and bottom tracks into the end bar and lock bar, so the whole gate resists being prised out as one piece.
Robust security comes down to the construction of the gate, the locks, the tracks, the bolts, the anchoring, and the wall working together as one system.
What to Look For Before You Buy
Before you compare prices, put the same questions to every supplier. The answers tell you much more than a photo or a quote ever will:
- Is the gate custom-built to your exact opening, or a standard size forced to fit?
- What steel is used, and how thick are the uprights?
- What lock is fitted? Look for high-security star-key hook locks, not a basic cylinder.
- What does the gate run on? Sealed bearings last; plastic wheels wear.
- Are any structural parts plastic, or is it steel where it counts?
- What are the rivets made of?
- Does it have a durable, weather-resistant finish?
- What guarantee comes with it, and how long?
- Who manufactures and installs it?
A supplier who’s confident in their products will answer all of these without hedging. Always ask to see a sample before you commit, because with so much on the market, it’s the only way to know what you’re paying for.
The DEFENDoor Range: DX-215, DX-310, DX-420, and DX-222
Not every opening needs the same gate. DEFENDoor builds four models in the retractable security gate range that step up in specification, so you can match the gate to the risk, the opening, and your budget rather than just buying the cheapest one on the shelf.
Here’s how our four solutions compare:
| Feature | DX-215 | DX-310 | DX-420 | DX-222 |
|---|---|---|---|---|
| Position | Entry | Mid-range | High security | Premium flagship |
| Uprights | 16mm steel | 19mm steel | 19mm steel | 19mm steel |
| Flights | 2 diamond crosses + half flight | 3 diamond crosses | 4 diamond crosses | 2 diamond crosses + 2 high-security 5mm zig-zag |
| Star-key hook lock | Single | Single | Dual | Dual |
| Rivets | Aluminium | Stainless steel | Stainless steel | Stainless steel |
| Bottom bolts | Spinning nylon-6 | Solid steel in glass-filled nylon | Solid steel in glass-filled nylon | Solid steel in glass-filled nylon |
| Construction | Steel | All steel | All steel | All steel |
| Guarantee | 2 years | 5 years | 5 years | 5 years |
- The DX-215 is the entry point: 16mm steel uprights, a single star-key hook lock and a two-year guarantee. It’s a solid, affordable choice for flats, estate homes, internal doorways, and secondary entrances.
- The DX-310 steps up to 19mm steel uprights, stainless steel rivets, all-steel construction and a five-year guarantee. For most homes it’s a sweet spot between price and security, and a good fit for front doors, patios, and sliding doors.
- The DX-420 is the high-security option, with four sets of flights and two star-key hook locks. It suits larger openings, high-value homes, offices, and retail.
- The DX-222 is our flagship design. It adds two sets of 5mm high-security zig-zag flights to 19mm uprights, dual locks, stainless rivets, and all-steel construction, for luxury homes, executive residences, and premises that need the most protection DEFENDoor offers.
How Much Do Retractable Security Gates Cost in South Africa?
There’s no single price for a retractable security gate, because every one is built to the opening. The only accurate figure comes from measuring your opening.
Prices vary with width, height, the model, the security spec, the finish, and the fitting, so the honest way to price a gate is to have the opening assessed and measured. DEFENDoor custom-builds to your opening rather than selling one-size-fits-all, and we even offer financing options for approved customers.
The Bottom Line: Never Buy on Price Alone
Though it might look it, a retractable security gate isn’t just a set of metal bars. The steel, the uprights, the track, the bearings, the locks, the rivets, the bolts, and the anchoring all decide how well it holds, and most of that is invisible once the gate is fitted. Two gates can look identical in a photo and be built worlds apart, which is why price alone is a poor guide.
Ask what steel is used, how the gate locks, what the rivets are made of and how it’s anchored, and you’ll quickly see the difference between a basic barrier and a properly engineered one. Whatever you call it, trellis, trelli, retractable, or concertina, DEFENDoor will measure your opening for free, recommend the right model, and custom-build it to your requirements.
Book your free security assessment today to receive exceptional service from an industry leader that cares about your safety. You can also call 0860 333 363 or email sales@defendoor.co.za for your free quote.
Whatever you call it, the right gate is the one that protects your home best. DEFENDoor has been doing exactly that in South Africa since 1995.
