A HABONIM Spring Return Valve Handle (rear view). It is used as a dead man's device to prevent uncontrolled spill while discharging a hazardous liquid.
<a href="//commons.wikimedia.org/wiki/User:Cccefalon" title="User:Cccefalon">CEphoto, Uwe Aranas</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>