http://pastport.jp/user/shiwoxinr0/timeline/Nema%2017%2017HS19-1684S-PG51%20Stepper%20Motor%20Bipolar%20L%3D48mm%20w_%20Gear%20Ratio%2051%3A1 https://www.oyostepper.com/goods-302-Nema-17-Stepper-Motor-Bipolar-L%3D48mm-w-Gear-Ratio-51-1-Planetary-Gearbox.html .This Nema 17 stepper motor with 48mm body and 1.68A rated current. ja-JP