MDT Spare Round Holder, Black, Polymer Construction, Fits M-LOK, Holds (2) Rounds 105248-BLK Have you ever run out of ammo mid-stage? Dropped mag or feeding issues" or simply need the extra round or two available when it counts? Store an additional 2 rounds on the side of your rifle with the MDT M-LOK Multi-Caliber Spare Round Holder.