Specification Brand : daier BulletPoint1 : Durable Material: The coupling connector is made of 45# steel( it is better than copper and aluminum alloys ), heat and electroplated process make it sturdiness and insulation, striking shaft more stable and easy for installment and replacement. BulletPoint2 : Widely use: used in model shaft connection, perfect accessories for RC Model motor. BulletPoint3 : Size:Inner Diameter: 8mm,Height:13mm,Fixed Hole Screw: M4. BulletPoint4 : Package included:4Pcs 8mm Flange Shaft Coupling + 1Pcs M4 Mini Hex Wrench + 8 x M4 Fastening Screw BulletPoint5 : Single piece set screw clamp design makes it easy to set up the items on the shaft and control the holding capacity of the coupling. Color : Dark Blue DriveSystem : External Hex ExteriorFinish : Aluminum,Steel ExternallyAssignedProductIdentifier1 : 044861351574 ExternallyAssignedProductIdentifier2 : 0044861351574 ExternallyAssignedProductIdentifier3 : 00044861351574 FinishType : Silver ItemName : 4Pcs 8mm Flange Coupling Connector, Rigid Guide Model Coupler Accessory, Shaft Axis Fittings for DIY RC Model Motors ItemPackageDimensions_Height : 10.1 centimeters ItemPackageDimensions_Length : 3 centimeters ItemPackageDimensions_Width : 7.2 centimeters ItemPackageQuantity : 2 ItemTypeKeyword : set-screw-couplings Manufacturer : daier Material : Metal MeasurementSystem1 : Metric MeasurementSystem2 : Inch MetalType : Aluminum MetalType1 : Aluminum MetalType2 : Alloy Steel MetalType3 : Copper ModelNumber : H420*4 NumberOfItems : 1 NumberOfPieces : 4 PartNumber : H420*4 ProductDescription : Parts for RC Airplane Boat ,DIY Model. Perfect accessories for RC Model motor, etc.