Outside diameter of ring 2.5" - Plated mild steel Ring and rod are integrated with boss head clamp Boss head clamps rods up to 5/8" in diameter with metal thumb screw Clamp from Boss head center line measures 8" to edge of closed ring. Plated mild steel with 5/16" diameter rod Plated mild steel with 5/16" diameter stem, with open boss head fitted with thumb-screw to accept rods from 5/16" to 5/8" dia. extension distance from boss head to ring is approx. 4.25", Outside diameter of ring 2.5" Clamp from Boss head center line measures 8" to edge of closed ring.