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, 7.62×39, 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 spacer system uses Mil Spec washers and O-Rings to offer the perfect fit. 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.