... rib, two ribs and three ribs on the top of shell could be done Lock type of back hoop: Turning knob (rachet), ... pull to adjust is ok Specific: Withstand a weight of 5kgs falling on to it if dropped 1 mete, can be used ... code GH060DescriptionSafety helmet with V rib with 6 cooling vents on top of the shellMaterialShell-ABSWeight380gAccessoriesFabric tape, buckle, pinlock, ratchetColourRed, Yellow, ...