Gear ratios and Gear box length: 
16mm gear bpx length based on gear ratios: 1/10 1/12.5 1/25 1/31.5
17.5mm gear box length based on gear ratios:1/50 1/62.5 1/78.1
19mm gear box length based on gear ratios:1/100 1/125 1/156.25 1/195.3
20.5mm gear box length based on gear rations: 1/312.5 1/390.6 1/488.3

Technical performance:
MBI-20A130-10-121300
Gear ratio: 1/10
Working voltage:12V
No load speed:1300r/min
No load current: 0.10A
On load:0.15kg.cm
On load current:0.35A
On load speed: 1000r/min
Stall torque:0.80kg.cm
Stall current:1.5A

MBI-20A130-25-06270
Gear ratio: 1/25
Working voltage:6V
No load speed:270r/min
No load current: 0.15A
On load:0.35kg.cm
On load current:0.45A
On load speed: 200 r/min
Stall torque:1.5kg.cm
Stall current:1.3A

Application: 

Robot, Curtain,Projector,Fingerprint Lock, Padlock, Vending Machine