DEROFIT Sliding Door Security Bar,2Pcs 16 to 51 Inch Inside Sliding Patio Door Window Security Bar Stopper, Adjustable Window Locks Security Bars for Home Apartment Security, Sliding Glass Door Lock Hardware

Why I tried this bar

Sliding doors and ground-floor windows are perennial weak spots. I wanted a simple, renter‑friendly way to add a second line of defense without drilling holes or swapping hardware. Over several weeks, I used the DEROFIT security bar on a patio slider and on two windows (one slider, one single-hung). It’s a straightforward concept—a telescoping metal bar that sits in the track to block movement—but the execution matters. Here’s how it performed.

Build and design

The bar feels more robust than the price and simplicity suggest. The white-finished metal tubing is thicker than the typical “tension rod” you’d use for curtains, and the joints don’t wobble when fully tightened. The ends are capped with rubber pads that sit securely in the track and don’t mar the surface. That detail matters on painted aluminum and vinyl tracks that scratch easily.

The adjustable range is 16 to 51 inches, which covers most windows and sliders, and it arrives as a two-pack. The telescoping/splicing design lets you set a precise length and then secure it with a pin lock. That pin (and the small key that accompanies it) is the most meaningful difference from a cut-to-fit dowel: once pinned, the bar resists compressing even under a hard shove, and it’s much harder for someone to “bounce” the door to wiggle the bar loose.

The bottom piece can be removed to switch between horizontal use in a door or vertical use in a window, which expands where you can deploy it. In white, it blends in with most tracks and doesn’t draw attention.

Setup and adjustment

Installation takes a couple of minutes, but there’s a little technique to getting the length just right:

• Clean the track first. A fine layer of dust or pet hair reduces friction and can encourage slipping, especially in vertical window use.
• Close the slider or lower the sash to the desired position (fully closed for security, or slightly open if you’re setting a vent gap).
• Extend the bar to the track length and insert the pin to lock that length. You want a firm wedge—snug enough to resist movement, not so tight you bow the track.
• Seat the rubber pads flat against the track walls. If one end rides up on a ridge or a screw head, rotate or reposition slightly until both pads have full contact.

On the patio slider, setup was easy: horizontal placement in the bottom track is straightforward, and once pinned, the bar doesn’t budge. On a single-hung window, using the bar vertically took more fiddling. Gravity wants to pull it down if you don’t preload it slightly. I found two tweaks that solved this: a slightly tighter wedge and positioning the top pad where the top sash has a flat, clean surface. After that, it stayed put without creeping.

If you’re fitting multiple locations with both bars, label them. Tracks that look identical can vary by a few millimeters; once you dial in each bar, you’ll save time later by returning it to the same spot.

Performance and day-to-day use

In everyday use, the DEROFIT bar does what a passive security device should: it adds friction and a physical stop to defeat casual force and opportunistic tampering.

• On the slider, it withstood hard shoulder checks without noticeable flex. The door flexes in its frame before the bar gives, which is exactly what I want to see. I can’t verify the 400‑pound claim with instruments, but I pushed harder than most intruders would risk, and nothing shifted.
• On the window, once set, it stayed locked at the height I chose. I left a three-inch gap for airflow for an afternoon; the sash didn’t creep, and with the pin set, there’s no easy way to compress the bar from outside to widen that gap.

For households with kids or pets, the bar doubles as a simple way to limit openings. It’s much more convenient than re-cutting a wooden dowel when you want a different vent gap, and the tactile feedback of the pin lock inspires more confidence than purely friction-based adjustable bars.

Noise and rattling were non-issues once the bar was properly wedged. If you’re hearing anything, you probably need a quarter-turn of tension or to reposition the pads for full contact.

Where it fits—and where it doesn’t

The 16–51 inch adjustment range is generous for most use cases: bedroom and office windows, standard patio sliders, and smaller balcony doors. It won’t span a wide opening if you want to secure a door partially open at a very large gap, and it’s not meant for outswing doors or casement/crank windows.

Because it sits inside the track, it works well for renters—no holes, no adhesives, no visible modifications. The white finish blends into aluminum and vinyl frames; it will stand out more on dark bronze or black tracks, but the footprint is still minimal.

The two-pack is practical: I set one permanently on the slider and kept the second for windows and occasional travel.

Portability and travel

This is one of the few track bars I’d actually take on the road. It breaks down quickly, and at a minimum length of 16 inches, it fits diagonally in a suitcase. Vacation rentals with sliders are common, and having a removable bar adds peace of mind without relying on whatever the host installed. It’s also handy in hotels with windows that still open (rarer these days, but still around). Do note that not every track or window design will accept a bar, so consider this a “nice to have” rather than a guaranteed solution away from home.

Trade-offs and quirks

No tool is perfect. Here’s what stood out:

• Fine adjustment takes a light touch. On vertical windows especially, you’ll need to find that sweet spot so the bar doesn’t creep down. It’s not difficult, but it isn’t entirely foolproof on the first try.
• The keyed pin is small. It’s easy to misplace. I’d clip it to the bar with a tiny lanyard or keep it in a dedicated drawer.
• Aesthetics are limited. White works for most interiors, but there are no alternate finishes. If you’re particular about matching black or bronze hardware, this will show.
• It’s a supplemental measure. This won’t replace a quality lock or laminated glass. Think of it as a second deadbolt for your slider or a physical vent stop for your window.

None of these were deal-breakers for me, but they’re worth factoring into expectations.

Practical tips

• Place the bar at the bottom track of a slider for best leverage and to keep it out of sight.
• If you’re setting a ventilation gap, choose a small opening that still prevents a hand or tool from reaching the lock.
• Clean tracks periodically. Grit reduces friction and can shorten the life of the rubber pads.
• Check the fit seasonally. Metal expands and contracts slightly with temperature swings; a quick snug-up keeps performance consistent.

The bottom line

The DEROFIT security bar hits a sweet spot: simple, sturdy, and renter-friendly, with a meaningful upgrade over a DIY wood dowel thanks to its pin-locked adjustability and grippy rubber ends. It’s equally useful as a pure “door closed” blocker and as a controlled vent stop, and the two-pack makes it economical to outfit a slider and a window without juggling parts.

I recommend this bar for anyone who wants a no-drill secondary lock for sliding doors and windows—especially ground-floor apartments, townhomes, and vacation rentals. It’s not a substitute for good primary hardware and common-sense practices, but as a quiet, robust layer of defense that takes minutes to install and seconds to remove in an emergency, it earns its spot in the kit.