What are the U-Shaped Prongs Used for in the Replacement QM3 - Quick Mount Hardware?

Updated 07/31/2025 | Published 07/24/2025

Question:

Can you tell me what the U shaped prongs on the end of the Tie Down Brackets ex. THO4997 are supposed to be used for? Thank you.

asked by: Mj

Expert Reply:

Hello Mj,

The U-shaped prongs in the Thule QM-3 Quick On-Off Mounting Kit # TH04997 are actually tie-down brackets that sit inside your cargo box. They’re there to give you a solid place to hook the included straps, so you can keep your gear from shifting around while you're driving.

Each bracket installs over the mounting bolts that attach your box to the roof rack. Once they’re in place, you can loop the tie-down straps through those U-shaped prongs to lock down whatever you’ve packed. It’s a simple but smart way to make sure everything stays secure, especially helpful if you’re carrying stuff that could slide or tip over.

What Thule roof mounted cargo box do you have? What do you mainly use it for?

expert reply by: Kate F

Tie-Down
(click to enlarge)

7/31/2025

Thank you for your response. I understand that the slots are for the straps but what are the u shaped prongs at the ends used for? See attached pic.

Kate F.

7/31/2025

@Mj Thanks for the picture, my apologies. The U-shaped ends on that bracket are there to hold the square-neck carriage bolts in place so they don’t spin when you tighten the knobs from inside the cargo box. It makes installing or removing the box way easier, you just slide the bracket over the bolts, and everything stays lined up nice and secure without needing extra tools. It’s a clever little design that really helps with quick on-and-off mounting!