Alpha-X / Race Master Insert BlockThe Alpha X and the Race Master Holsters utilizes an efficient and easy system to allow shooters to switch their holster from one gun type to another by means of changing the Insert Block Assembly. This switch is fast and easy and can be done in less than a minute, and without losing any of the holster's adjustments or settings. The Insert Block Assembly includes: The Locking Block (gun specific). The Sliding Lock, assembled (gun specific). The safety