Plugging in a battery can create a loud spark at the connector which is caused by the high battery current rushing into the low ESR capacitor first as well as filling up ESC capacitance. We’ve added a protective circuit to extend the lifespan of XT60 connectors and prevent rapid voltage or current spikes which can protect your electronics from damage. iFlight offers this in 3 sizes. This is their "version 2" measuring 25x18mm.
Check out the Rest of our iFlight product range and PDB/BEC selection while you're at it!