You must have these if you remove your chain for any reason, you can not reuse the old power link. If you are using the Sarm Red or Force 12 speed AXS groupsets this is the powerlock to get. MAKE SURE you get the right powerlock there are others that look the same but will not work, The power lock is easy to use ,you just have to line it up right so it snaps in correctly and locks the arrow on the power lock has to point in the direction of the pedal stroke, moving forward. If you have not used them before might want to get 2 sets just incase of a mistake, i installed mine and was just a little off on lining it up and only half snapped in and i could not get the other side to snapp closed i had to remove it and you cant reuse it cuz one side was locked and not the other, dam it, any ways buy 2 and your covered.