Iron plated universal joint can rotate and change the transmission direction. Suitable for car models and ship models, small and delicate, durable.Product Description:Name: Universal joint couplingMaterial: iron electroplating (45 # steel)Product description: For example, 4mm-5mm, i.e. 4mm and 5mm holes on both sides, can be inserted and fixed with shafts or motors of corresponding size and diameter.Use: motor, straight shaft, suitable for model cars, model ships, robots and other types of metal transfer use!Dimension introduction: (data is for reference only, please refer to the actual object)2. 3mm-2.3mm.2mm-2.3mm. 2mm-2mmUniversal Joint Outside Diameter: 8mmUniversal Joint Length: 18mmSide Screw Fixing Hole: M32. 3mm-3mm. 3mm-3mm. 3mm-3.17mm. 3. 17mm-3. 17mm. 3.17mm-4mm.3mm-4mm. 4mm-4mm.2. 3mm-4mmUniversal Joint Outside Diameter: 9mmUniversal Joint Length: 23mmSide Screw Fixing Hole: M33mm-5mm, 3.17mm-5mm, 4mm-5mm, 4mm-6mm, 5mm-5mm, 5mm-6mm, 6mm-6mmUniversal Joint Outside Diameter: 11mmUniversal Joint Length: 23mmSide Screw Fixing Hole: M45mm-8mm, 6mm-8mm,6.35mm-8mm, 8mm-8mm(this model is designed to be fixed with a snap ring, so it is a bit tight, which is normal)Universal Joint Outside Diameter: 14mmUniversal Joint Length: 35mmSide Screw Fixing Hole: M4Fixed Clamp Spring Design8mm-10mm, 10mm-10mmUniversal Joint Outside Diameter: 16mmUniversal Joint Length: 35mmSide Screw Fixing Hole: M4Package Include:According to your Choose!