This thing is more about printable threads than a turnbuckle. Print without support, it's all in the geometry! In a nutshell : M10 printed male and female threads that are printed horizontally for extra strength and better print resolution. Most printers have better XY resolution than Z so this has the advantage of: http://www.gyrobot.co.uk http://www.facebook.com/gyrobotuk Print without support, it's all in the geometry! For this turnbuckle, each end has a right hand (RH) and a left hand (LH) metric M10 thread. The left hand thread is denoted by the letter "L" in the stl model and "LH" in the filename. This means you turn in opposite direction to conventional threads. You can change the length of the turnbuckle by rotating the inner buckle clockwise or anticlockwise in relation to the ends. You can print either the eyelet or hook ends for RH or LH threads. I have supplied two buckle stl files, one has extra thread clearance should your printer's calibration or flow rate print too tight. You might want to clean the threads up by running a metal nut or bolt through the threads to clean up any oozing or print defects. Finally, a little lubrication helps the threads run smoothly too.