Make your Tokyo Marui M4 GBB Rifle have an ambidextrous bolt catch with the Laylax First Factory Ambi Bolt Catch... "It is a tactical item to make the bolt catch ambi & large. The lever is arranged along the lower frame so it does not interfere with the trigger operation and the lever jumps out from the lower frame greatly when the bolt catch is activated so that it is possible to realize a reliable and speedy bolt release with the trigger finger.