A Bird 43 inline RF power meter
<a href="https://en.wikipedia.org/wiki/User:Signalhawk" class="extiw" title="en:User:Signalhawk">en:User:Signalhawk</a>
English Wikipedia, <a href="https://en.wikipedia.org/wiki/File:43_general-purpose-wattmeter.jpg" class="extiw" title="en:File:43 general-purpose-wattmeter.jpg">en:File:43 general-purpose-wattmeter.jpg</a>