This is a full "aircraft" type headset with sound-insulated speakers for both ears, and a boom microphone. It adjusts to suit the wearer's head size etc. It is ideally suited for use in places where the background noise is very loud. Obviously wearing this headset will muffle ambient noise, so it is only useful where radio messages are more important than "outside" sound - perhaps use in motorsport, light aircraft, industrial applications, camera operators filming live music performances, etc.
The Kirisun walkie-talkies generally use either the "K1" Kenwood twin-jack socket, OR the "M1" Motorola twin-jack socket.
The PT558, PT4200, PT5200 all use the Kenwood "K1" socket.
The PT568 used the Motorola "M1" socket.