The Plantronics CS540 is the lightest headset on the market, the CS540 has DECT technology that removes Wi-Fi interference and the battery life gives it up to 7 hours talk time. Pair up to three other users for conference calling and choose from three diverse wearing options. Adding the the reliable Plantronics APP-51 Hook Switch cable with your Plantronics C054 wireless headset enables the ability to answer/end calls when away from your Polycom phone. Without APP-51 Hook Switch cable, you will have to answer/end calls when at your desk phone. No longer needed as I don’t work in an office
eBay