JSP EVO Alta Baseworker With JSP Sonis Ear Defenders Hard Hat KitCombining a hard hat and ear defenders in one package, this kit ensures that youll always have the necessary safety equipment on hand. Both components are genuine JSP products, guaranteed to be compatible. The mountaineering style helmet is EN 397 compliant, with a chin strap designed to release under force. Its also electrically insulated, and has an internal EPP liner for side impact resistance. The wheel ratchet adjuster gives you a secure fit.