Screw mainly used in stepper motor, Machine Tool, and other equipment. Screw without processing, direct connected to bearing. Suitable for Industrial automation equipment, stepper motor rails; such as 3D printers; engraving machine; module; slider; lifts etc. color: gold+silver Lead screw: Material: stainless steel Diameter: 8mm spacing: 2mm Total Length: 500mm Screw nut: Material: brass Diameter: 8mm Mounted ball bearing: Material: zinc alloy Bore diameter: 5mm Hole diameter: 8mm Total length: 55mm Height: 29mm Shaft coupling: Material: aluminium Shaft: 6.35 x 8mm Length: 24mm Diameter: 18mm How to install: 1. Pls put screw nut into the Lead screw 2.Then the 2 Mounted ball bearing separately install at both ends of the Lead screw 3. According to the size of you need to adjust the distance between the nut and Mounted ball bearing 4. Put shaft coupling into the Lead screw beside the Mounted ball bearing Package Contents: 1x Lead screw 1x Screw nut 2x Mounted ball bearing 1x Shaft coupling Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.