Sennheiser Enterprise Solution 615104247284 SD 10 HS VOIP Telephone Headset Headset for SD Pro base Single-sided Premium Wireless DECT headset The flex-a-fit wearing style system offers the choice between a headband, ear hook or neckband solution for the perfect customized fit. The neckband is available as an optional accessory. Active Guard technology protects against acoustical shock Ultra noise cancelling microphone