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