Hard plumbing Reefer 350

[Brooks Allman]

Does anyone have a link to where I can buy an adapter from the sump side of the red reefer 350? I want to hard plumb my return but I cant seem to find the adapter size because I believe it is metric. Does anyone have a link to one that would work?
Thanks!

 

[143MPCo]

https://flexpvc.com/cart/agora.cgi?product=PVC-Fittings-Metric-Adapters