This is a set of 3 lead screws with precision bronze nuts. A great set for that home made cnc lathe, mill, printer or router. Each screw is 12" long and 14 mm diameter with a 10 thread per inch pitch ( 0.100") One end of the screw has a 12 MM machined section 21 MM long for your bearing and a 14 MM section threaded 10 MM X 1.5 with a self locking nut. The bronze nut is 25 MM long and 28 MM in diameter on the un-threaded portion. The threaded portion is 13 MM long by 20 MM diameter with 16 threads per inch. The nut also has flats milled on each side for a wrench. The nut can be mounted in a round bracket and held with a set screw, or could be threaded into a bracket built with matching threads.