| 摘要 |
A helmet which is characterized by a rounded top and a shaped cowl provided with two sets of spaced slots defined by three tracks spanning an open lens window for receiving a transparent lens slidably mounted in an outside set of parallel slots and an optional tinted lens mounted in an inside set of parallel slots, for closing the lens window. In a preferred embodiment the transparent lens is a tear-away lens connected at a perforated interface to the next one of several additional lenses wound in end-to-end relationship in a roll, which roll is located inside a canister attached to the cowl of the helmet. Each transparent lens on the roll is individually, selectively and sequentially extended through a feed opening in the canister and through the parallel outside lens slots to a track lip projecting from the opposite side of the cowl, when the preceding lens is so damaged or coated as to adversely affect visibility and is slidably removed from the lens tracks. When the damaged lens is slidably extended from the lens slots in the face mask cowl for removal, a second lens is automatically unrolled from the canister and slidably positioned over the lens window and the damaged lens is torn from the leading edge of the newly positioned lens at the perforated interface between the lenses.
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