This is a "D type" earpiece/ microphone. So-called, because the piece that fits over the wearer's ear is shaped like a letter D.
It fits over the wearer's ear, is made of soft,flexible plastic, and has an inline microphone with PTT button and a clip to attach it to the wearer's clothing.
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.