Store an additional 2 rounds on the side of a rifle with the MDT M-LOK Multi-Caliber Spare Round Holder. Wide range of round compatibility including .223, 300 AAC, .224 Valkyrie, 7.62x39, 6.5 Grendel, .308, 6.5 Creedmoor, 450 Bushmaster, 7mm, 300 WM, 300 PRC, 6.5 PRC and more. Includes a small and large caliber polymer body with adjustable spacer system for maximum compatibility. The holder can be mounted using M-LOK or the accessory holes on the side of ACC chassis. The reversible design allows for mounting on left or right side of chassis.