Adds the ability to adjust the length of pull (LOP) of your X-Ray Gen 4 without the use of tools or spacers. The thumbscrew adjustment can be swapped to either the left or right side. Maintains the tool-less buttpad height and cant adjustments that come standard on the X-Ray Gen 4 & 5. Fits: X-Ray Chassis (Gen 4 & 5 only) Restrictions: Not compatible with Gen 1-3 X-Ray Chasssis Weight: 4oz Material: Reinforced polymer