This is a retro mobile phone receiver that allows you to be more comfortable when answering calls. More suitable for people who communicate on the phone for a long time The Telephone Handset has 3.5mm Round Socket;Handset Size:21x5x6cm/8.27x1.97x2.36'(LxWxH);Cable length:1M/3.28FT This phone handset has an answer button and a volume button, you can adjust it according to your needs, with a 1-meter extension cable, you can easily answer calls Steps of intallation:1. When there is a call on the mobile phone, use the Telephone Handset plug to point the hand socket;2. Press the answer button Only works with 3-channel 3.5mm audio socket,before purchasing, please confirm the size of plug