A bench block is something we use frequently at our bench. We use it when knocking out a pin or to hold a round object, preventing it from rolling. The rifle block is a 1-1/8 inch thick polyethylene round (4 inch diameter) block with a v-through milled in it. Holes are drilled through for knocking out pins. Polyethylene material protects the finish of what you're working on. This handgun block has grooves designed to hold slide assemblies.
Sinclair, Issue:4A, Page:248