Features: A1 Focusing construction Connectiong objective: DIA 76mm Connectiong pillar: DIA 25mm/32MM Adjustable distance:50mm Easy Large-Sized Focusing Knobs on Both Sides of Focusing Holder Steel Gears on Focusing Holder Standard Size Focusing Holder - Will Fit Scope Heads with Diameter of 76mm Features: A3 Diameter of annular ring maintaining microscope head: 76mm Tail connection diameter:16mm Adjustable distance:50mm Packing including: 1 x Microscope Adjusting Bracket