Lathe 40 Position Quick Change Tool Post size A1. (Some manufacturers and dealers call this model size A). Can be used on BV20, SINO210V, D240, CQ6125 bench lathe which turning diameter is from 150 to 300mm(6″-12″). One set A1 includes: 1 X 540-100 tool post and locking wrench. 3 X turning facing tool holders A1D2090. Can hold 20 MM (20/25″=0.8″) shank turning tool. Will hold tool 8mm to 20mm. 1 X boring turning facing tool holder A1B2090. 1 X Tool Clamping T wrench. The spline of the tool holders are EDM cut, not fine ground. Canada, USA and some European countries like France, Norway, etc. PLEASE REFER TO DIAGRAM IN PICTURE MODEL NAME- A1(540-100) D20. Cam-lock handle rigidity locks & quickly releases the tool holder. Correct height of cutting edge is easily & accurately adjusted by special set screws 3. Tools can be reground without removal form tool holder so the setting remains unaltered 4. 40 different angles are conveniently selected from position dials with marker. Holders are interchangeable with most other brands of 40 position tool post. Tool Post:HRC 50±2 degree after heat-treatment. Toolholder:HRC 42±2 degree after heat-treatment. Basic body and tool holder are made of high-quality steel which is hardened and ground. The tool holder is clamped against the basic body by an eccentric cam system The system allows a repeat accuracy of 0.01 mm with 40 possible angular positions of the tool holder. Quick-change tool holders are characteried by their unlimited diversity in the use of lathe tools, drills, reamers and boring bars. Includes 3 standard holders & one boring holde. CONTENTS- THIS SET CONSISTS OF ONE MAIN BLOCK, 3 STANDARD HOLDER, 1 BORING HOLDER AND HANDLE SUITABLE WITH TOOLPOST.