Part # 2/3A600 : 1.2 volt 600mAh rechargeable NiCd flat top battery cell.  Cell dimensions: 0.67" diameter x 1.12" tall. Choose Plain, or with Solder Tabs (tabs are $ 0.25 extra per cell. Solder Tabs enable easier assembly of the battery cells; they are welded on top & bottom at 180' angle to each other.

Pricing is for 1 cell. Picture shows two aspects of the battery cell.