Panasonic Kx-tga560s Silver 5.8 Ghz Fhss Gigarange&reg; Expandable Digital Cordless Handset Handsets for use with Panasonic base models KX-TG5631, KX-TG5632, KX-TG5633, KX-TG5634, KX-TG5651, KX-TG5652, KX-TG5653 KX-TGA560S Silver Handset The last number in the phone modem represents the total number of handsets that a telephone system can operate *Replacement or New Handsets require registration, Check your user guide for procedure **Defective batteries do not charge past 1 bar and will turn on & off when trying to operate them