Spiral flow membrane module.
<a href="//commons.wikimedia.org/wiki/User:Daniele_Pugliesi" class="mw-redirect" title="User:Daniele Pugliesi">Daniele Pugliesi</a>
CC BY 3.0
<a href="//commons.wikimedia.org/wiki/File:Spiral_flow_membrane_module.jpg" title="File:Spiral flow membrane module.jpg">Image:Spiral flow membrane module.jpg</a>