@Fless called it! Double male barbed coupler and a release tool. For the tool, I've never had one of these let me down:
https://www.amazon.com/ARES-70024-3-16-Inch-Scissor-Disconnect/dp/B0195XBPPQ
Although, you won't be needing it to install your repair parts.
If it weren't for ethanol, I'd pick the double barbed fitting over the compression union, unless that double barb is stainless. If it is zinc-coated steel as it appears to be, you did good ordering those plastic compression unions. If they ever leak, get stainless double barbs.