I have no idea if they are all built the same. I have the one they made for Howa mini using the mags they made specifically for howa mini using this very bottom metal.
The bottom metal is high quality. However, it doesn't lock the mag perfectly in place. They don't interface perfectly with one another and the mag has a millimeters of play up and down. This is detrimental to feeding because it only feeds reliably in the upmost position.