Audicom H201STAC Corded Office Telephone RJ Headset with flexible Noise Canceling Mic for Aastra Shoretel Cisco E20 Polycom 335 VVX400 Digium D40 D70 Altigen 500 720 Comdial & Starleaf IP Phones Direct connect over-the-head headset, No additional amplifiers or adapters required, Most easy setup headset solution. ONLY WORKS FOR SOME SPECIFIC PHONES. SEE COMPATIBLE PHONE LIST IN DESCRIPTION, BUY THE ITEM TODAY IF YOU HAVE ONE OF THE PHONE MODELS LISTED BELOW. Noise canceling microphone to reduce background noise and Acoustic Shock Protection circuit to protect your hearing. Super Lightweight, Super Durable Headset with Comfortable ear and mic cushions, Shirt clip included. NO Mic Mute / Volume Control built in.