Panasonic KX-TGA405B Range Extender for DECT 6.0 Plus Cordless Phone Systems Also sold separately as an accessory Included with select 2010 models Compatible with Panasonic KX-TG7500, KX-6500 and KX-4000 series cordless phone systems For DECT 6.0 Plus Cordless Phone Systems Doubles the effective transmission distance between the base unit and the cordless handset