Ultimate Arms Gear Meprolight The Mako Group M21 X Self-Powered Day/Night Reflex Sight with Dust Cover - X Reticle 3/32 Pin Punch Tool Package Includes: Meprolight M21 X + Ultimate Arms Gear Pro Disassembly 3/32 Pin Punch Armorers Gunsmith Tool Ultimate Arms Gear Tool Diameter is 3/32 of an inch or 2.5mm. Small and compact with enough size and strength to do all that is needed in taking apart pins and putting it together.