This is the Subminimal product I recommend most to friends who are getting serious about espresso. It sits on the rim of your cup and gives you a close-up view of extraction from a bottomless portafilter: channeling, flow rate, grind issues, all visible in real time without crouching under your machine. I keep mine magnetically mounted on my Breville between shots, so it's always within reach. The tempered glass is thin, nearly weightless, and the slight tint gives your shots a cinematic quality that makes the whole experience more satisfying. It's a simple object that quietly makes you a better barista.

I wanted to like this item, but I already went through 2 of them. One broke when I slightly dropped it on the countertop, my fault but it was not that high of a drop, and the other one had the mirror just pop off. I was able to put it back on and still using it, but this is the one item that subminimal makes that meh.

I was in need of a mirror to monitor my shots so I don't have to work my knees/quads so hard and this works pretty well. I did find an issue with the adhesive not being strong enough so the mirror does pop out of the frame, but it isn't terrible. When I tried placing it on my cups, it works fine, but takes a little bit of finesse to get it to stay and to get a good angle, so mostly I place it on the drip tray. Overall, I like the product.