Wireless call system. 1)ts could be andheld for Disabled, Elders, Patients, Children, ... all main units: work with GDH100, GDH400, GDH500, GDH300Long Life of battery: one year 50 calls in a dayBenefitsEasy to operation ... requirementsMain unit (controller): GDH100, GDH400 GDH 500, GDH300System pictures best price of wireless calling bell for hispital or elder