Stacool Roof Rack Mounting Brackets, 4PCS U-Shaped Clamps for Roof Boxes — Universal Fit to 3.35" Crossbars, Rust-Resistant

Stacool 4PCS U-shaped roof rack mounting brackets are a complete universal kit to securely clamp roof boxes and cargo carriers to most roof racks using U-bolts, nuts, rubber washers and straps.

If you need a simple, heavy-duty replacement or an upgrade to attach a roof box, cargo carrier or rooftop tent, this Stacool kit supplies four plate brackets, four U-bolts, eight nuts, rubber washers, two straps and a sealing sticker. The parts are sized to fit crossbars up to 3.35" (85 mm) wide and 1.06" (27 mm) thick; check your rack dimensions before ordering. Materials and finish are selected to resist weather and daily vibration so your load stays put on highway and backcountry drives.

How do these brackets keep a roof box from shifting on the road?

The U-shaped clamps wrap under and around the roof rack crossbar, creating a solid mechanical grip that resists lateral and vertical movement. Combined with rubber washers and properly torqued nuts, the assembly transfers load forces to the rack instead of allowing slippage.

• U-bolt clamps cradle crossbars for positive hold.
• Rubber washers damp vibration and protect finishes.
• Locking nuts secure torque and prevent loosening over time.

Will these brackets fit my vehicle’s roof rack crossbars?

They are designed for universal compatibility with most aftermarket and OEM crossbars, within the kit’s specified size limits. Measure your crossbar width and thickness—if your crossbar is ≤3.35" wide and ≤1.06" thick, these brackets will fit properly.

• Suits square, round and many aero-style crossbars within size range.
• Includes sealing stickers for hole protection on some installations.
• Two webbing straps add clamping redundancy and ease of use.

How durable are the Stacool mounting brackets in outdoor conditions?

The kit uses corrosion-resistant materials and a weather-tolerant finish to stand up to rain, sun and road salt. Components are engineered for repeated installation cycles and long-term use, making them suitable for frequent travelers and seasonal storage alike.

• Rust-resistant hardware extends service life.
• Rubber washers remain flexible in heat and cold.
• Straps and plates withstand UV exposure and abrasion.

What tools and steps are required for installation?

Installation is straightforward with basic hand tools: a wrench for the nuts and a tape measure to confirm fit. The kit’s parts are pre-matched, so assembly follows a simple clamp-plate-U-bolt sequence and final torque to secure the load.

• You’ll need a wrench or socket set for nuts.
• Measure crossbar dimensions before starting.
• Tighten nuts evenly and use straps for extra stability.

Who this is for: drivers who own roof boxes, cargo carriers or rooftop tents and want an affordable, durable mounting solution that fits most crossbars. It’s ideal for weekend adventurers, families adding cargo space for trips, and anyone replacing worn or missing clamp hardware. If your rack measurements fall within the kit’s limits and you prefer simple, mechanical fastening over vehicle-specific mounts, the Stacool 4PCS U-shaped mounting bracket kit provides a practical, weather-resistant way to secure rooftop cargo.