B&T Industries AAIS Bottom Rail: 1913 bottom rail option for BT19 and BT21 BT20-B

The BT20B AAIS Bottom Rail is the same rail found in the BT20 but has the bottom of the M1913 rail that only can be attached to the AAIS BT19 on the bottom at the 6 o'clock position. This allows the mounting of the BT10, BT10-LW17, or the AAIS BT19. The rail is 1.60" long.