This is a 6 cell (7.2VDC) 2200mAhr Rechargeable NiMH battery pack.
The batteries are NiMH so they do not have the memory issues common with NiCad battery packs. The batteries are arranged in a 1x6 array of AA batteries interconnected via soldered strips and covered with a PVC wrapping. Two wire leads extend out of the pack.
As an options below you can select to get 15A connectors for the batteries. The connectors are sometimes referred to as Anderson Powerpole connectors. They can be soldered/crimped onto the wire ends and offer a great way of disconnecting the batteries for charging, etc.
Use these roll pins to fix sprockets to a shaft and keep them locked in place.