Cable APP-51 Electronic Hookswitch communicates electronically with the phone, eliminating the need for a HL10 lifter. Works with the following products Savi 700 Series: W745, W740, W730, W720, W710, W740-M, W730-M CS500 Series: CS540, CS540/HL10, CS530, CS530/HL10, CS520, CS520/HL10, CS510, CS510/HL10 MDA200 Savi Office: WO100, WO101, WO200, WO201, WO300, WO305 ***Replacement Note: The APP-51 EHS cable replaces the APS-50 cable and features compatibility with the Plantronics On-line Indicator accessory*** Part Number: 38439-11