JW Winco's Wing nut with tapped through insert. Tapped through wing nuts allow full clamping, unrestricting the threaded stud the wing nuts is being used on. Maximum heat resistance of nylon plastic: 110 degree C (230 degree F). Wing body: Matte black, glass filled nylon plastic. Tapped through insert: Brass, molded-in. RoHS Compliant. Head measures 48mm length by 17mm width by 20mm height.