These useful clamps can be put to multiple uses round the studio they fit to most standard light stands and can be used to hold boom arms in place the double clamp allows you to attach a boom arm or any other type of lighting accesory to the frame of your light stand instead of the top studspigot this means you are still able to use the top studspigot of your light stand to attach any other lights or accesories you want clamp has 4 different diameter holes for locking different sized boo