The kreg klamps fit in 5/16 track but not 1/4 inch track. It is likely that you could replace the screw with a smaller head and get it to work in 1/4 inch track. I've never needed to replace the screw so I haven't bothered to find out what size it is.

I think the rubber pad on the kreg klamp is a good/useful feature. I also like having the different length reaches. There is a standard and a longer reach klamp. It is a tool which is worth the premium price, IMO.

I use kreg klamps most often when I use the Domino.