Item: Chain coupling The chain coupling, composed of two-strand chains and two sprockets, features simple and compact structure, and high flexibility, power transmission capability and durability. What's more, the chain coupling allows simple connection/disconnection, and the use of the housing enhances safety and durability. Material:Carbon steel,Brass,Stainless steel,etc Tolerance: 0.01mm-0.02mm Type 3012, 4012, 4014, 4016, 5014,, 6020, 6022, 8018, 8020, 10020, 12022 Model :KC Service:OEM,ODM,OBM