EP300AA : 1.2 volt 300mAh 1/3AA rechargeable Ni-MH battery cell. Size: 0.625" tall, 0.56" diameter. Weight: approx 1/3 ounce. Available Plain, or with Solder Tabs (one on top, one on bottom - for assembly) for $ 0.25 extra per cell.
Pricing is for one battery cell; picture shows 2 views of the battery cell.