Feature: Fixed Couplers are used to Connect Stepper Servo AC DC motors to Ball screw or Lead screw they are widely used to build CNC Router, CNC Plasma, CNC Mill, CNC Laser and many automation machines. Widely used in hardware,molds, and the occasion of the mechanical transmission. Suitable For: connecting two axis with different diameters, can also be connected with a motor axis, or connecting shafts of different diameters. Between the transmission member can do both screw can do model remote control boat propeller shaft and the motor power. Specification: Material: Brass Color: Golden Connection diameter: 8 x 8mm Top Thread Size: M3 Through Angle:90 Degree Dimensions: 22 x 16mm/0.87 x 0.63"(L x Dia) Package Include: 2 x Motor Rigid Coupling 1 x Allen Wrench 8 x Screws