The holes for the bolts are drilled imprecisely. I have a Thor400 box that I had no issues mounting on the X7 rails. The WTF rails have one hole visibly misaligned. I have a picture but there is no way of posting it here.
Another issue, more severe - they are small for the ThunderCat BTG tire. It's like 1 mm between the tire @ 16 psi and the Fungineers battery.
I don't have any other BTG-compatible rails, so I have to keep them. If I had something else, I'd return them right away.