This is a "headband" type of headset that has a speaker over one ear, and a boom microphone.
It adjusts to suit the wearer's head size etc. It is ideally suited for use in situations where the wearer needs to keep hands free as much as possible.
These headsets are sometimes called "Madonna" or "Britney" headsets, because they look a little like the mics worn by those two ladies on stage.
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.