The plate reads:
<p>BLUE ORIGIN
</p><p>BE-4 ROCKET ENGINE
</p><p>Part no. 004-150-0000-001
</p><p>Serial no. 101
</p><p>Master eWO 36491
</p><p>Mfg date October, 2017
</p><p>Made with Pride in Kent, Washington USA
</p>
"The BE-4, originally serial number 101, was manufactured in Kent, Washington during October 2017. It was the first BE-4 engine to be hotfire tested, on 18 Oct 2017. It has subsequently been hotfire tested, disassembled, rebuilt and retested several times to its current iteration in this photo, noted as SN 103.  Portions of this development engine have gone through desctructive (<i>sic</i>) disassembly and inspection."
<a href="//commons.wikimedia.org/wiki/User:N2e" title="User:N2e">N2e</a>
<span class="int-own-work" lang="en">Own work</span>