How to connect motor to gearbox?

[Doszhan]

Good day.

I've bought MCP4 gearbox. Photos is below (sorry for quality):



I found DC motor, which can be suitable for me: http://www.aliexpress.com/store/product/5pcs-63ZYT02A-12v-electric-brushed-dc-motor-3000rpm-100w-O-D63mm-rated-voltage-12-volt/418322_1562300377.html

Question is how to connect DC motor to gearbox? DC motor has smooth tube, gearbox has smooth tube docked with the edge. If I just put motor's tube onto gearbox's tube, they will not connect.

[Doszhan]

I found adapter that comes with this gearbox, so I found the answer. I just need to grind off the edge of tube of motor. Radius have to be the same as gearbox's.