2″ dia. plastic washer used for attaching continuous rigid insulation (ci). Prongs enable pre-spotting into insulation (for fast on-the-wall fastener assembly). Use with Grip-Deck® screws/fasteners to attach rigid insulation including extruded polystyrene (XPS), polyisocyanurate (polyiso), mineral/rock wool, etc. Use as tested, specified or recommended by every major insulation manufacturer.