| 摘要 |
<p>A helmet having a front shell and a rear shell movable with respect to each other. Portions of the two shells overlap each other and present mating surfaces which can engage to retain the shells in a given overlapping position and can disengage to allow the shells to change their relative position. A device is provided for selectively (a) holding the mating surfaces in engagement, or (b) releasing them to disengage.</p> |
