BAK Revolver X4S vs X4TS: Which T-Slot System Fits Your Rack?
When you’re choosing between the X4S and X4TS models in our Revolver lineup, the decision often comes down to how you use your truck bed. Both covers feature the same aluminum slat construction and rolling mechanism, but their rail systems differ in a way that matters if you carry crossbars, ladder racks, or rooftop cargo boxes.
The X4S uses a flush-mount aluminum rail that sits nearly level with the bed sides, while the X4TS integrates raised T-slot channels designed specifically for attaching aftermarket accessories. We built both systems to solve different real-world loading challenges, and understanding which one matches your setup saves you from buying twice.
How the Rail Profiles Differ
The X4S rail sits flush with your truck bed’s top edge, creating a low-profile appearance when the cover is rolled up or removed. This design keeps wind noise minimal and maintains clean bed access for tall cargo that reaches the full interior height.
The X4TS rail stands about 1.5 inches taller and features machined T-slot channels running the length of both side rails. These channels accept standard T-bolt hardware, which is the same mounting system most aftermarket rack manufacturers use. BAK Industries engineered this interface to eliminate the need for drilling or custom brackets when you add crossbars.
What the Height Change Means
That extra 1.5 inches reduces your usable bed depth slightly — not enough to matter for most loads, but enough that a stacked pallet or an extra-tall toolbox might require the cover to stay partially open. The tradeoff is worth it if you regularly mount kayak carriers, bike trays, or cargo baskets that demand a secure anchor point above the bed rail.
Rack and Accessory Mounting
If you never plan to add crossbars or roof-style accessories, the X4S gives you everything you need without the extra rail height. The flush design works with most bed-mounted tie-downs and doesn’t interfere with fifth-wheel hitches or gooseneck installations.
The X4TS was built for trucks that do double duty — hauling loose cargo one day and carrying rooftop gear the next. The T-slot channels accept any crossbar system that uses industry-standard T-bolts, including Thule, Yakima, and Rhino-Rack models. You can install and remove crossbars in minutes without tools beyond a basic hex key.
Bed Access With Crossbars Installed
When crossbars are mounted, the X4TS cover still rolls open fully, though you’ll need to route the bars slightly forward or aft depending on your cargo. We’ve tested this configuration with two crossbars spaced 24 inches apart, and the cover operates normally as long as the bars don’t sit directly over the roll mechanism’s resting position.
Weatherproofing and Seal Performance
Both models use the same EPDM rubber seals along the perimeter and between slats, so water resistance is identical when the cover is closed. The X4S has a slight advantage in high-speed rain because the lower profile creates less turbulence at highway speeds.
The X4TS rail channels include drain holes at quarter-panel intervals to prevent water from pooling inside the T-slots. If you live in a region with heavy snow, check these drain ports monthly during winter — ice buildup can block them and create standing water that eventually seeps into the bed.
Seal Replacement
Replacement seals for the BAK Revolver X4S Hard Roll-Up Tonneau Cover and X4TS use the same part numbers for the main perimeter gasket, but the X4TS includes two additional short seals where the T-slot channel meets the end caps. These extra seals rarely need replacement unless the rail takes impact damage, but they’re available separately if you ever need them.
Installation and Bed Fit
Both covers install with the same clamp-on system — no drilling required, and removal takes about five minutes if you need full bed access. The X4S clamps sit entirely below the bed rail’s top edge, so they’re invisible from outside the truck.
The X4TS clamps are identical in function but position slightly higher to accommodate the raised rail. This doesn’t affect security or stability, but it does mean the clamp housings are visible from certain angles when you’re standing beside the truck. If appearance matters more than accessory mounting, that’s one detail to consider.
Weight Difference
The X4TS rail extrusions add about 4 pounds to the total cover weight compared to the X4S, bringing the installed weight to roughly 64 pounds versus 60 pounds. That difference won’t affect handling during installation, but it’s worth noting if you remove the cover frequently and store it off the truck.
Choosing Based on How You Use Your Truck
The right model depends on whether you value a lower profile or the flexibility to mount accessories. If your truck bed stays dedicated to hauling loose cargo, tools, or gear that doesn’t need overhead attachment points, the X4S delivers a cleaner look and maximum bed depth.
If you regularly switch between bed cargo and rooftop loads — bikes, kayaks, cargo boxes, or ladder racks — the X4TS eliminates the hassle of drilling or custom brackets. The T-slot system is a proven ISO-standard interface used across the outdoor gear industry, so you’ll have no trouble finding compatible accessories as your needs change.
Both covers share the same rolling mechanism, sealing technology, and aluminum construction, so either choice gives you reliable bed protection. The decision comes down to how you plan to use the space above your bed rails.
Common Questions About X4S and X4TS Compatibility
No, the rail systems aren’t interchangeable as retrofit parts. The X4S and X4TS use different side rail extrusions that are integral to each cover’s frame assembly.
If you purchase an X4S and later decide you need T-slot functionality, you would need to replace the entire cover rather than swap individual components.
Yes, both the X4S and X4TS are available in the same bed length configurations for most full-size truck models. Fitment is determined by your truck’s year, make, model, and bed length — not by which rail style you choose.
Check the manufacturer’s fitment guide to confirm compatibility for your specific truck before ordering either model.
The T-slot rails themselves are rated for the same static load as most aftermarket crossbar systems — typically 150 to 200 pounds distributed evenly across two crossbars. Dynamic load ratings depend on the specific crossbars and accessories you install.
The cover’s aluminum slats are not designed to support standing weight, so always ensure crossbars span the full bed width and transfer load to the truck’s bed rails rather than resting on the cover itself.
The X4TS T-slots are designed for crossbar systems that mount along the bed’s length, not for bike racks that clamp directly to the cover’s surface. If you need a bike rack that attaches to the tonneau itself rather than to crossbars, the X4S is the better choice — its flush rail provides a stable mounting surface for clamp-on accessories.
For vertical bike carriers that mount to crossbars, the X4TS is ideal because the T-slots give you adjustable crossbar positioning.
Both covers install over spray-in and drop-in bed liners without modification. The clamp system adjusts to accommodate the liner’s thickness, typically adding about 0.25 inches to the rail height measurement.
If you have a bed liner with raised stake pocket covers, measure the total height from the bed floor to the top of those covers — the clamps need at least 0.5 inches of clearance below the liner’s top edge to secure properly.
The T-slot channels should be inspected and cleaned every few months, especially if you drive in dusty or muddy conditions. Debris can accumulate inside the slots and interfere with T-bolt placement.
Use a stiff brush or compressed air to clear out dirt, then wipe the channels with a damp cloth. Avoid spraying lubricants directly into the slots — they attract more dirt and aren’t necessary for T-bolt function.