Perfect design, exquisite workmanship, and high performance. Lightweight and portable, high quality with durability in use. Made of metal, easy to install on your RC car. The coupler improves vehicle stability, cornering, and brake efficiency. Specially designed for 1/10 HSP Axial SCX10 D90 HPI RC car crawler. Specification: Material: Metal Color: Red Suitable for: Hub 5mm, Axle screw 4mm Hex: Approx. 12mm / 0.47in Length: Approx. 15mm / 0.59in Weight: 29g per piece Package Includes: 4 x 12mm Hex 15mm Couplers 1 x Set of Screws Spare Parts Note: Due to differences in monitor displays, the picture may not reflect the actual color of the item. Due to manual measurement, there may be a 1-2mm error in size.