ITEM NAME:Aluminum Alloy Shaft Coupling Flexible Coupler Motor Connector Description: For a 5mm stepper motor shafts to your 8mm threaded rods (it's 5mm to 8mm coupler) Material: Stainless steel Shaft: 5 x 8 mm Size (DxH): 19 x 25 mm Package Includes: 1x Coupler SKU: DMO0012956151000576.For a 5mm stepper motor shafts to your 8mm threaded rods (it's 5mm to 8mm coupler). 1x Coupler. Shaft: 5 x 8 mm. Material: Stainless steel. SKU: DMO0012956151000576.