Strong polyurethane ear cup straps Adjustable sizing with hook and loop velcro Fits David Clark Sigtronics Racing Radios Electronics Standard on Rugged H42 and H42-ULT headsets Velcro BTH head strap for behind-the-head style headsets. Fits most behind the head headsets were over head strap attaches to ear seal groove. Like Racing Radios, Racing Electronics, David Clark, Sigtronics, and many other brands.