A standard motor pulley for T2.5 belts. 16 teeth, so works as a drop-in replacement for a 8-tooth T5 pulley.Some say that this part is a vitamin, but I didn't believe them.I printed this with 0.35 nozzle, 0.20 layers, 0.36 tracks and 10 secs per layer, with PLA.I produced this from droftarts' http://www.thingiverse.com/thing:11256, but I only hacked it until I got this specific standard size pulley to print correctly, so the .scad file isn't really a publishable derivative...