Telikou BK-101Z/4 is a single channel Electret button belt pack with call vibration function. PTT (push to talk) and Latching Microphone button Call button; Call light; Volume control Sidetone adjustment XLR-3M and XLR-3F Loop-through Intercom connectors XLR-4M headset connector 3.5mm headset connector The BK-101 is compatible with TELEX and Clear-Com Party-Line intercoms