Compatibility Guide: This RJ9 IP Phone Headset ONLY Compatible with Acsergery Cisco IP Phones such as 6921, 6941, 6961, 7931G, 7940, 7941G, 7942G, 7945G, 7960, 7961, 7961G, 7962G, 7965G, 7970, 7971, 7971G, 7975, 7975G, 8941G , 8961G ,8945G, 9951G, 9971G, CP-7821...etc. DO NOT BUY if your phone is not a Cisco IP Phone. Details pls check Compatible Guide in DESCRIPTION. Pls ask us for advice if youre not sure about the compatibility . Superb Sound Quality for Communication: This RJ9 Headset equipped with Acsergery noise cancelling microphone can screen unwanted background noise. Make sure your voice can be heard clearly and loudly. And with Acsergery HD Audio Speaker, callers voice will be transmitted in clarity. Make sure you can communicate with Acsergery each other smoothly and happily. . Built for Comfortable: Adjustable Headband fits all different size head and Flexible microphone boom offers you proper position. Ergonomic design Light weight call center headset with Acsergery ultra soft leatherette ear cushions and silicon T-Pad make you comfortable enough to wear it all day. This Office Headset also equipped with Acsergery Acoustic shock protection circuit, which can screen the sudden noise caused by static. Provide International standard hearing protection to your ears. . Extremely Durability: This telephone headset is designed with Acsergery Reinforced stainless steel headband, high impact and abrasion resistance plastic, Uni-body construction for lasting use. High reliability PU cable with Acsergery Tensile Fiber protects your wired headset from stretching and trampling. All these features make it be competent for high frequency use in home office call centers school hospital... . Due to international sales, there may be slight differences in appearance between different batches, please be aware