High-quality material: The universal connection nut is made of high-quality alloy steel material, which is strong and durable.CNC mechanical design: 4mm motor coupler has a special design, perfect workmanship, precise size, convenient and quick installation and disassembly.360-degree rotatable universal joint: This mm joint count can change the transmission direction at any point, which is very flexible and easy to use.Application: 4 mm rotation coupling is perfect for remote control model and remote control model boats, as well as perfect motor shaft assembly accessories.Material:alloy steelcolour:SilverPackage Contents:8 x Cardan Coupling Connector16 x screws4 x WrenchOnly the above package content, other products are not included.Note: Light reflection 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.