28mm diameter low noise planetary gearbox CE,RoHS compliant 13,17.5,21.5,26Kgf-cm torque reduction ratio:from1/ ... 3.4,3.8,4.4,5.3,6.742.7 12,13,15,16,18,19,20,23,26,28,35,4551.3 ... ,85,95,102,106,121,129,152,184,233,29659.9 296,327,375,405,447,534,637,760,860,965 ... ,1016,1136,1304,1556,1975 28mm Low noise Planetary gearbox 13~26Kgf-cm CE RoHS