The mini ERA is called a Hornet. I still use them on my minis. It's a solid
rba. Mine are stainless steel. It's got a smaller air chamber, tighter draw, closer posts, less working room, feeds from one of the posts, and because of that has no drain hole for excess
juice to flow back into the bottle. But they are a decent vape - miles better than a carto.
They have a push on cap secured by 2 orings. I pull off one oring and use it in the catchup before screwing the atty on. That way I can get things positioned exactly where I want them, and I get no leaks (other than if I over-squonk and forget to vape it out.) I also prefer the airier draw of the RM2 and had to drill out the Hornet air holes a bit.
Price-wise, the RM2 is the better deal. The Hornets were about $74 a piece.