Check the listing for details. Octo Stop Block - Quick-adjust Measuring Block for fixture/welding table. Condition: New. Listed at 22.95 USD. The Octo Block alignment tool fits into any 5/8"(16mm) fixture table hole and features 8 sides to quickly adjust for any distance in 1/4" increments. Each block includes two center pins which can be swapped; a standard pin for 1/4" increments and an eccentric pin to allow fine adjustment under 1/4". Blocks have center-line marks on both sides for easy reference and mirrored setup. 3D printed from PETG for good UV and heat resistance (need to be removed during welding). This handy tool - or a few of them - make it quick and easy to jig custom parts on a fixture table for precision fabrication. - Comes with 1 Block and 2 pins - Say hello to quick and accurate fixturing like never before - Each block includes two center pins, one center and one eccentric pin - Features 8 sides to adjust for any distance in 1/4" increments - Swap to eccentric pin for any finer number than 1/4" - 4 blocks is ideal for fixturing