The actual holding power of the clamp is hardly acceptable. However, if you buy this kit you are throwing away the fasteners, screw, washer and cheap plastic handle with a poorly bolted metal insert. The screws on all four clamps I bought were rusty, poor quality and with an extra thin sub-standard screw head. Probably suitable for the too small Fuchs T-rail, which I also bought but immediately returned. I would return these brackets as well, but I really needed something quick. They appear to be painted rather than anodized, and when they are, the paint will come off your project if you're not careful. I do not recommend these brackets. Spend a little more and buy from Woodpeckers or Incra. I expected more from Shop Fox.