Small drain fitting

[Baby Blue]

I’m looking for a small drain sitting similar to the photo. The drain size is only approx 5/16” and it drains a small cooler on our 2800SCR.
Can’t seem to find anything online but maybe not using the right terminology.
Thanks
Mark

[Laminar]

Hello Mark,

Not sure if you've already found a solution, but McMaster-Carr is great for little things like this.

Here's an option:
https://www.mcmaster.com/sealing-plu...ip-round-caps/

Or this:
https://www.mcmaster.com/sealing-plu...pansion-plugs/