I bought this because I wanted to get something that could grind espresso, since I have an espresso machine now. More on that later, but the short version is that if you're using the same type of machine I am then you probably can't make espresso with real espresso grind.I have been using the Fellow Ode Gen 2 for a while, and it's done a pretty good job for my pour over, French press, Aeropress, and the espresso machine. My boss got the Opus though, and I decided to look into it, and on the Fellow website they say this machine is for making espresso, and that the Ode explicitly DOES NOT make espresso. I used my Kruve sifter to check the size of the grind on my Ode at the lowest setting, and... they're right. I looked around, and the general belief is that espresso should be between 200 and 400 microns. A comically low amount of the grinds were in that range from my Ode. So I decided to get a grinder that can handle the espresso grinds, and figured I was happy with the Ode, so I might as well get another Fellow product.Once I received the thing, I set about making espresso with it at the lowest setting, and it... didn't work. It turns out my espresso machine isn't actually able to make espresso if you have the grounds between 200 and 400 microns, but this review isn't about my espresso machine - it's about the Opus! So let's talk about the Opus. The noise level is lower than many of the other grinders I've used. I can't say I'm thrilled with how the push button system works on this. I've become accustomed to the automatic stop that comes from the Ode, so having the burrs keep spinning LONG after the grinding was done is a bit of a disappointment.Does this machine ACTUALLY grind espresso? Yes, and no. Right out of the box it comes with the inner ring at the middle point, and with it at the factory settings on the lowest setting of the outer ring I took 20 grams of grounds and put it through the Kruve and it looks like 10 grams was in the 200-400 micron range (50%) and 9.5 grams was above 400. The remaining .5 grams was below 200. I am going to say that it's very likely that if I were to adjust the inner ring and make it finer there's no question that this machine would be able to get more of the grounds below the 400 mark. I don't want to sit here forever trying to get the exact right setting though, because it takes a lot of effort to sift things in the Kruve (really... a LOOOOONG time). I put about a pound of beans through trying to dial it in for my espresso machine (and that took about 2 hours) only to find out that my machine can't actually use anything finer than what my Ode was able to produce. If I happen to get fired up and want to REALLY dig in on the particle size, I will update this review; but I don't foresee that happening.Pros:- Grinds espresso fine all the way up to French press (or whatever you use that's coarse). Exactly as advertised.- Lightweight.- Reasonably quiet.- You don't need tools to adjust it.Cons:- The grind consistency is lacking. Can't say I'm terribly surprised. I think every grinder I've encountered has had puffed up claims about grind consistency, and they have all fallen quite short. This one is no different than the rest.- Retention. Oh, my gosh... the retention on this thing is INSANE. Watch the video. I don't remember where, but when I first saw this thing (probably last year...?) and as I was perusing around they were mentioning it had "Zero Retention" which I guess was a misnomer. They advertise "Low Retention" now that I look back at their marketing material. I don't know who on their team defined "Low" but that person needs a dictionary. SWEET MOTHER OF MERCY this thing has a lot of retention. If you want to get the grounds out, you CAN get it to where you get out all that you put in. You just gotta smack, shake, jostle, and otherwise abuse the thing to make it give up the grounds.- The build quality is lacking. The magnet in the bottom of the grounds container is really weak, and doesn't do a great job of centering it. Also: the whole thing is made of really cheap feeling plastic that gets scuffed and scratched amazingly fast. The lid on the hopper is covered in scratches. Yes, I used it like a bellows to try and cope with the absurd levels of retention (it doesn't help, by the way. Don't bother trying. You gotta shake it like it owes you money to get the grounds out). It still got scratched up SUPER fast. Like... within the first 3 times I used it the thing looked like it was taken through a war zone. The whole machine is light as could be, and it really tells the tale of how much they decided to skimp on materials and engineering.If you're going to get a grinder, I honestly can't recommend this one. For the price - It's REALLY not that great. I was torn between getting the Baratza Encore ESP and this, and decided since the Ode was really quiet compared to the Baratza Encore I owned previously that I'd go with the Fellow product again. Yes the Encore was louder, but it felt a much higher quality. I might go looking for a bellows for this thing, and I'll probably keep using it for a bit. More than likely I'll go back to the Ode though. I'm pretty disappointed. Maybe someday I'll get a REAL espresso machine that can handle actual espresso grinds, and I'll be able to dust this thing off and let it go to work.