This is a <a href="https://en.wikipedia.org/wiki/Choke_(electronics)" class="extiw" title="en:Choke (electronics)">choke</a> with two 47 mH windings. It can take up to 0.6 A at 230 V. You might find it in a power supply, blocking high-frequency interference. Potographed with ruler for scale.
<a href="//commons.wikimedia.org/wiki/User:Mike1024" title="User:Mike1024">Mike1024</a>
2007-10-11
Photographed by <a href="//commons.wikimedia.org/wiki/User:Mike1024" title="User:Mike1024">Mike1024</a>