Iron plated universal joint can rotate and alter the transmission direction. Suitable for car units and ship models, small and delicate, durable.Reminder: This product would not include a wrench, and the wrench should be purchased separately.Product Description:Name: Universal joint couplingMaterial: iron electroplating (45 # steel)Product description: For example, 4mm-5mm, i.e. 4mm and 5mm holes on either sides, can be inserted and glued with shafts or motors of corresponding length and diameter.Use: motor, straight shaft, suitable for model cars, mannequin ships, robots and different kinds of steel transfer use!Dimension introduction: (data is for reference only, please talk over with the particular object)2-2; 2-2.3; 2.3-2.3 (diameter 8mm, size about18mm)2.3-4; 3-3; 3-3.17; 4-4; 3-4; 3.17-3.17; 3.17-4; 3-2 (diameter 9mm, length about 23mm)3-5; 4-5; 5-5; 6-4; 6-5; 6-6 (diameter 11mm, length about 24mm)5-8; 6-8; 8-8 (diameter 14mm, length about 34mm)8-10; 10-10 (diameter 16mm, length about 35mm)Screw accessories:3-4, 4-4, 3.17-4, 4-2, 2.3-4, 2-2, 2-2.3, 2.3-23, 2.3-3, 3-3, 3-2, 3.17-3.17, 3-3.17 (with 2pcs three * 4 meter screws)4-5, 5-5, 6-4, 6-5, 6-6, 3-5 (with 2pcs four * four machine meter screws)8-8, 5-8, 6-8, 8-10, 10-10 (with 4pcs 4 * four machine meter screws)Package Include:According in your Choose!