Using the same bottom metal body, you can change from BDL to Magazine-fed anytime in minutes. It is revolutionary and the first of its kind in many ways. It is the only all-aluminum ultra-lightweight magazine system that allows you to make your BDL rifle a magazine-fed rifle while only weighing 5.4 oz. The kit uses a BDL configured body with proprietary cuts, and a tensioning system to allow the all-aluminum M5 magazine to fit snugly or remove the magazine and tensioner and attach the lid (sold separately,) converting it back into a BDL. This is the magazine kit which includes the Bottom Metal Body, Tensioner, M5 4-Round Capacity Magazine for Standard Cartridge 2.850" OAL or 3-R Mfg: Snowy Mountain Rifle Company