This is a high speed carbon brush 37mm DC motor 12V, model 540, 14000RPM.
Specifications:
Rated Voltage: 12V
Speed Current 12V test: speed 12500 rpm approx.
Motor length: 50.7mm
Motor Diameter: 37.3mm
Step diameter: 13mm
Step HeightL 4 mm
Fixed aperture: 3mm
Fixed hole distance: 25mm
Shaft length: 18mm
Shaft diameter: 3.175mm