Package including: 1pcs malicious program tools reducer NMRV030; Please write Ratio you wish after order. Offer Ratio:5:1,7.5:1,10:1,15:1,20:1,25:1,30:1,40:1,50:1 60:1,80:1 . The matched 57mm flange NEMA23 stepper motor size: 1,shaft diameter=11mm; 2,Rabbet =38mm;3, diagonal Screw hole distance= 67mm. If you wish the 6.5mm to 11mm shaft putting in sleeve, you can buy it here: https://www.aliexpress.com/store/product/shaft-installing-sleeve-6-35mm-to-11mm-for-NEMA23-stepping-motor/1932111_32814689522.html If you wish the 8mm to 11mm shaft putting in sleeve, you can buy it here: https://www.aliexpress.com/store/product/shaft-installing-sleeve-8mm-to-11mm-for-NEMA23-stepping-motor/1932111_32814725307.html If you wish output shaft to compare the trojan horse tools reducer ,we supply single output shaft and double output shaft 1,single output shaft: https://www.aliexpress.com/store/product/single-shaft-Worm-gear-reducer-output-shaft/1932111_32815592282.html 2,double output shaft: https://www.aliexpress.com/store/product/Double-shaft-Worm-gear-reducer-output-shaft/1932111_32817703115.html