This Nema 8 stepper motor with 30mm body and 0.6A rated current, integrated with a 25.7mm Planetary gearbox of 19:1 gear ratio. It's a good solution to applications that with special space but need low speed and/or high torque.
 
Electrical Specification ： 
Manufacturer Part Number: 8HY0001-C19X
Motor Type: Bipolar Stepper
Step Angle: 1.8 deg
Holding Torque without Gearbox: 18mN.m
Rated Current/phase: 0.6A
Phase Resistance: 1.6ohms
Voltage: 3.9V
Inductance: 3.2mH ± 20%(1KHz)
 
Physical Specifications : 
Frame Size: 20 x 20mm
Motor Length: 30mm
Gearbox Length:25.7mm
Shaft Diameter: Φ6mm
Shaft Length: 15mm
Number of Leads: 4
Lead Length: 500mm
Weight: 300g