This King Arms metal hop up is designed for those who have upgraded their Tokyo Marui plastic bodies to metal bodies. Most plastic body M4/M16 have two piece hop up units, when upgrading to a metal body you also need to upgrade to a metal hop up unit. This is the perfect metal hop up to get because it will seal against the gearbox, flawlessly feed BBs, and it is fully adjustable to put the right amount of backspin on each BB.
King Arms M4 Hop Up Unit Package Includes:
Alternate Lookup: KA M4 HOP UP