These are my favorite clamps! 3/4 is better than 1/2" because teh 3/4 pipe doesn't bend AND the 3/4" jaws are much better guided on the pipe so is less likely to bow the boards being clamped. The multi-disc pipe gripper works every time and lasts for many years. The Sears style pipe clamp feet tend to slip on the pipe so I have to hold them against the pipe while tightening. I often use a pipe coupling to extend my pipe for the wide boards I clamp.