The underside of several key caps of the Schneider MF2, a membrane computer keyboard manufactured by Cherry from 1988. They are dual molded plastic, and some larger keys have extra support to stabilize them.
<a href="//commons.wikimedia.org/wiki/User:MarcoTangerino" title="User:MarcoTangerino">MarcoTangerino</a>
<span class="int-own-work" lang="en">Own work</span>