Plantronics EHS APC-42 Hook Switch Intended for: Phone Designed For: Plantronics MDA200; CS 510, 520, 530, 540; Savi W710, W710-M, W720, W720-M, W730, W730-M, W740, W740-M, W745, W745-M; Savi Office WO100, WO101, WO200, WO200/A, WO201, WO300, WO350 Product type: Hook switch