BBM supplies the A21PX also known as the EN133A , A21 - 4.5 V Battery. See below for full list of battery part numbers:
Fits Model: PC133A, 523, PX21, EN133A , A21 battery , A133
| Battery Attributes | |
| Capacity | 0.65Ah |
| Battery Type | Cylindrical Cell |
| Voltage | 4.5V |
| Chemistry | Alkaline |
| Terminal Type | Flat Top |
BIN - 1006