Item Type: Hex Coupling Material: Brass Product Height: Approx. 18mm / 0.71in Hex Diameter: Approx. 12mm / 0.47in Inner Diameter: Approx. 7mm / 0.28in Application: RC motor shaft, remote control car tire shaft, etc.1MAIN FUNCTION: Hex coupling is mainly used to connect RC motor shaft, hex tire shaft, DC motor and robot, etc. , simple and practical. 2BRASS MATERIAL: These hex couplings are made of excellent brass with good wear resistance, which are not easy to deform or corrode. 3EASY TO INSTALL: Equipped with mechanical screws and wrench, these hex couplings are easy to install and disassemble, with good practicability. 4SPECIFICATIONS: Including 10pcs 12mm hex couplings, with inner diameter of 7mm, standard size for easy installation and replacement. 5FINE PROCESSING: With fine workmanship, these hex couplings have glossy appearance, do not hurt hands or damage other parts during use. 10 x Hex Couplings 1 x Wrench 20 x Machine Screws