To apply simply place the nipple between the bars and turn the screw. The bar will start to apply pressure on the nipple. You can turn the screw until you feel that there's enough pressure being applied. Without the nipple in place, the two bars can meet together -- meaning that great pressure can be applied during use.For additional sensations, there's a key ring attachment connected to each nipple clamp. Sure, you could have your partner actually carry your keys around, but you could also apply weights to the attachment that just adds more to the stimulations.
Specifications: Fully extend the two bars are spread .75" apart. The clamp measures 1.5" in width.