The Kinetic Research Group 2 Slot M-LOK Weight is designed to add weight to the forend of your chassis for better balance and stability. Each individual weight takes up two M-Lok slots and can be stacked side by side on forends with 4 or more available slots. The size and shape has been optimized to provide a comfortable thumb-self for your non firing hand for alternative shooting positions. Weights are sold in pairs. Fits: W-3 Pro, W-3 (Gen 7), C-4, X-Ray, and Bravo chassis or other chassis/forends with two or more M-Lok slots.