This design needs a hex 1/4 inch to 1/4 inch square socket adapter which Anders did not need. but this puts out more torque and would break if it used Ander's design of having the 1/4 inch square portion made from pla. Also this design is flatter so I can mail out free ones with all orders of block v3 from my store (gr5store.com). Olsson block only needs 0.8nM but Block V3 needs > 1nM to prevent leaks sometimes. So I aim for 1.5nM. Around 4nM the nozzles will sheer and self destruct. 2nM is safe. Read instructions (materials and methods section) before printing!