This Nema 17 stepper motor with 39mm body and 1.68A rated current, integrated with a 48.3mm Planetary gearbox of 50:1 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: 17HS15-1684S-HG100
*Motor Type: Bipolar Stepper
*Step Angle: 0.018 deg
*Holding Torque without Gearbox: 39Ncm(55oz.in)
*Rated Current/phase: 1.68A
*Phase Resistance: 1.6ohms
*Voltage: 2.7V
*Inductance: 3.2mH ± 20%(1KHz)

Gearbox Specifications

*Gearbox Type: Planetary
*Gear Ratio: 100 : 1
*Efficiency: 65%
*Backlash at No-load: 2.4°
*Max. Permissible Torque: 15Nm(2124oz.in)
*Moment Permissible Torque: 20Nm
*Max. Radial Load: 100N
*Ambient Temperature: -10 - 90℃
*Insulation Class: B
*Noise: *Life: 20000 h

Physical Specifications

*Frame Size: 42 x 42mm
*Motor Length: 39mm
*Gearbox Length: 58mm
*Shaft Diameter: Φ8mm
*Shaft Length: 23.5mm
*Key-way Length: 14mm
*Number of Leads: 4
*Lead Length: 320mm
*Weight: 880g

Connection

Black(A+), Green(A-), Red(B+), Blue(B-)

Warning:

Make sure the motor connect to a constant current or chopper drive controller before you test motor.
Connecting the motor directly to a power supply will destroy the motor.