CROSSTAC ARCA Block. With the grooves machined into the blocks, these are meant to give you the traction and stability to make any PRS barricade shots out there. The blocks feature a QD mount in the base to do sling tensioning, and the grooved exterior helps prevent side to side slip but still allows easy release vertically. Machined window for extra versatility.
Mounts not included - price is per each.