This is a ball-bearing dual-arm heavy-duty boom stand for stereo microscopes. The ball-bearing design allows users to make horizontal adjustment at the touch of a finger. The holder ring of the focusing rack is 3" (76mm) in diameter. This boom stand weighs about 40 lbs. It is brand new in factory sealed box. Features & Specifications: Ball-Bearing Design for Easy Operation Easy to Make Horizontal Adjustment the Touch of a Finger Versatile Dual Arm Boom Covering Large Working Area 22-1/2" Horizontal Double-Arm 24" (605 mm) High Pillar 15" x 10" x 1" (380 x 254 x 25 mm) Solid Cast Steel Base 40 lbs in Weight Manufactured under ISO 9001 Quality Control Standard Excellent Five (5) Year Factory Warranty Unbeatable Low Price Guaranteed or the Difference Back! Satisfaction Guaranteed or Your Money Back! Packing List: One Dual-Arm with Ball Bearing Design One Focusing Rack One Pillar One Solid Cast Steel Base User's Manual