Coming from predominantly brewing pour overs, I'm just beginning my espresso journey. I started off brewing with my American Weigh 2kg scale under the porta filter but the combination of the occasional leakage from the group head and moist steamy air coming up from the drip tray made it malfunction after pulling a couple shots (It's since dried out and is fine). My Acaia Pearl is far too large to go under the group head and I'm not prepared to drop another few hundred on a Lunar. Enter this lovely little shot glass. It might not be as accurate as a scale, but it's good enough for my purposes. I can get pretty good idea of the grounds in, coffee out ratio by weighing my ground beans before hand and then watching the espresso rise in this glass. Echoing what another user said, I do wish it was maybe a little wider at the mouth, but for $8 I can't complain. Would definitley buy again and might buy a second to keep on hand in case I ever drop my first one. Although, it is quite heavy with thick walls so would likely stand up to a small drop.