Russian aviation (27 volts) relays TKE5 series. T — relay coil on 27 V, K — contactor, E — x amps, 5 — 5 amps.
<a href="//commons.wikimedia.org/wiki/User:Vivan755" title="User:Vivan755">Vivan755</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>