OctagonStar Flexible Couplings 5mm to 8mm NEMA 17 Shaft for RepRap 3D Printer or CNC Machine（2PCS） Description Flexible shaft couplers used in small CNC machines and 3D printers such as Prusa i3 or ORD Bot. Flex capability of the coupler removes stress when shafts are not aligned perfectly. Brand Listing,Item package or product surface have OctagonStar brand identity, If you buy is not OctagonStar brand product, You Can Apply for a Refund and Compensation. Features: Flexibility of this coupler removes stress between motor and driving component. Compatible with NEMA 17 stepper motors (for 5mm to 8mm shaft diameter). Useful in RepRap 3D Printers and small CNC machines. Dimensions: 19mm x 25mm. NOTE:OctagonStar Quality Assurance.Item package or product surface have OctagonStar brand identity. If you feel to buy isn't OctagonStar item, you can return or exchange. Product Details: Material: Aluminum Color: Silver Brand: WIKMOB Item Dimensions LxWxH: 0.98 x 0.79 x 1.57 inches Item Weight: 0.01 Ounces Is Discontinued By Manufacturer ‏ : ‎ No Product Dimensions ‏ : ‎ 0.98 x 0.79 x 1.57 inches; 0.01 Ounces Item model number ‏ : ‎ OS16208 Date First Available ‏ : ‎ June 20, 2016 Manufacturer ‏ : ‎ OctagonStar Best Sellers Rank: #85,326 in Industrial & Scientific (See Top 100 in Industrial & Scientific) #1,384 in 3D Printer Accessories #1,384 in 3D Printer Accessories Customer Reviews: 4.5 4.5 out of 5 stars 288 ratings