Cams also known as 'friends' are pieces of protection that can be used in parallel-sided or slightly flared cracks. They work by pulling on the "trigger" (a small handle) that retract the lobes together. The cam is then inserted into a crack, the trigger is released and the cam expands. The lobes produce outwards pressure on the rock when falling, stopping a fall. They can help you protect a placement where a nut may not work.