Anyone have recommendations for a good mag coupler? Universal preferably. The Lancer one seems promising out of what I found online.
Magpul has couplers called the Maglink but don’t know if they fit other mags then Magpul.
For which mags?
I use the Magpul PMag couplers from RJK Ventures - but it looks like they’re stepping away from sales currently due to some family issues (Small company).
@Krdshrk back in the house!!! Did I miss your arrival? 
I have mags from Magpul, Lancer, traditional steel, Troy Hex mags, etc. Ideally something universal.
I’ll take a look at RJK.
These are the ones I use more, now that I see they may be going away I wish I purchased more.
Now that you led me down a rabbit hole to find mag couplers, which I didn’t find what we want. I did stumble upon this, which I purchased and will let you know how well it works if you like.
Update: I picked up some Lancer couplers. They seem to work well. I have them on both Hexmags and Pmags, no problemo. They hold their position just fine. ~$25 for two from Primary Arms.
I used to couple my mags with some tape and cardboard. I’m getting a redi mag for one of my rifles.