Ultra Light* pupil gauge is a quality, rugged, yet affordable penlight. It features a pocket clip and push button endcap switch. Superior brightness. Approximately 5 1/4inch in length. Uses two AAA batteries, included), blue
Support Ring, Steel Rod, Steel rod, zinc-plated support ring with attached boss head clamp and thumbscrew, Distance from support to center of ring is 4-1/2in for all sizes, Diameter: 4