I use these to hold some toms and cymbal arms on my Millenium rack. The large screw at the rack side makes it easy to get the clamp really tight onto the rack, if necessary. I've never experienced any unwanted movement or slipping. The only negative observation I have made is that the side with 2 screws feels a little plastic-y, so I would maybe watch out for this if you intend to loosen and tighten the clamp many times (e.g. gigging, touring, etc).