... 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: press ... helmet with V rib with 6 cooling vents on top of the shellMaterialShell-ABSWeight380gAccessoriesFabric tape, buckle, pinlock, ratchetColourRed, Yellow, WhiteSize52- ...