Replacement PLF 423042 A1 PLF423042A1 Battery for Sirius S50, S50-H1, S50-SB1, S50-TK1, S50EX1-RET, BS50PK1-S50H1 & S50-TK1-H1 Portable Satellite Radio Receivers 3.7-volt 500 mAh lithium-ion battery. Replaces the following Sirius Battery Models: PLF423042A1 & PLF 423042 A1. Manufactured to have superior performance over the OEM original battery. 1 Year Replacement Warranty MPF Products is a Registered Trademark.