This single-arm heavy duty boom comes with a solid steel pillar and a long solid aluminum arm. The diameter of the holder ring is 3 (75mm). It is an ideal stand for gemologists collectors engravers and engineers in industries. This stand is in factory sealed box. Features & Specifications: 3 (75mm) Holder Ring 24 Overall Length 19 Single Arm 16 High Pillar 10 x 10 x 3/4 Solid Cast Steel Base Shipping Weight: 45 lbs