Shop now at Ubuy Panama. Lightweight, American-made accessory for MS3, MS2, VCAS, and VTAC slings. Shop now at Ubuy Puerto Rico. . Lightweight, American-made accessory for MS3, MS2, VCAS, and VTAC slings. Enhance your Magpul UBR with CSAP MOUNT-N-SLOT. Also includes the same detachable rubber buttpad found on Magpul CTR and UBR. Enhance your Magpul UBR with CSAP MOUNT-N-SLOT. Slot molded in the toe provides an attachment point for a 1¼" wide sling.