Material:ABS,PE,PP,HDPE Light weight,Good strength,Good toughness use for working of construction, aerial working Anti-shock Material: ABS, PE, PP, HDPE is available Color: red, blue, yellow, white, black, orange is ok Rib: one rib, two ribs and three ribs on the top of shell could be done Lock type of back hoop: Turning knob (rachet), Press button and inserting is ok Lock type of chin band: ...