Our new rail adapter makes it easy to a rail mount attachment or Rail Mount Brace or Blade System to your Century Arms C39 Pistol. Our adapter mounts to the rear of your receiver through the sling hole once the sling loop is removed. The Rear Rail can also be removed to use the adapter and mount a flat mount stock or flat mount folder as well. This part number for the Adapter with small machined aluminum rail, threaded inner block with all the bolts and installation instructions. Adapter and rail both made of machine 6000 series aluminum. **IN THE COMMENT SECTION OF YOUR ORDER, TELL US IF YOU HAVE A 1ST GEN, 2ND GEN (V2) OR RAS MODEL. The angle on the rear of the receiver is different.