I've worked out with weights at the gym for years, never bothered with home gym equipment because they tend to cheaply made, take up space and ultimately are no more convenient than just going to the gym ... and then COVID-19 hit and everything changed. I am at that age (63) where if I go for 1, 2 or maybe 3 months waiting for the gym to open I might never be able to get back to in shape. Dumbbells are a key part of my workout, I need them for bench chest press, seated shoulder press and shoulder shrugs. I use 80, 75 & 70 for chest press, 55, 50 & 45 for shoulder press and 90, 85 & 80, for shrugs. I would need a lot of separate weights which can be expensive and take up a lot of space. The format is key, I am only 5'8" and weight 150lbs, so when I do the 80's on the bench press I need to rest them on thighs/knees and then use my legs to help me get them up, so the typical adjustable where you screw on the weights won't work because the won't comfortably rest on my legs. The only two options being the bowflex and these. The bowflex appear to be very good as the look like a regular dumbbell with a slick way to change weights, however I had the occasion a few years back to try them and wasn't impressed as they didn't seem very solid (too plasticy), they don't really rest flat on your thigh and it is hard to find the set that goes over 55lbs. These seem ideal, as I got the stage 2 and 3 to get up to 90lbs and they will fit flat on you leg. The concern was that look like some rinky dink thing you would see on an infomercial. Plus you put your in this odd looking bear trap cage thing. But while they look rinky dink, they are actually very robust and an intelligent design. Most of the gym stuff that I've gotten only have to be 'good enough' to bridge me over for a few months and not something I would get if I were building a serious home gym, but these are much better than 'good enough' and they are a reasonable alternative to proper dumbbells if space and convenience is an issue. While I prefer the fixed weight dumbbells at the gym, the compromise you make for space savings and flexibility is not too significant and I could see these being part of a serious home gym. They may become a permanent option after COVID for the days I can't drag my butt to the gym. It is still a compromise vs. proper dumbbells but if you are looking for adjustable like these, then you will be impressed. The Bowflex may look pretty, and these not so much, but these are more durable and usable.

update 11 June:
now that I have been using them for a few months, I am even happier with them than I was before. Their Compact heavy duty weight stand is a must, but at only $69 it is well worth. It holds the weight at the right height to work with, a big plus is that it keeps things lined up so that the plastic pin slides in and out easily.

I researched adjustable dumbbells for weeks before making this purchase. No regrets here. They are easy to adjust and built to last a lifetime! I like how I can adjust away from the stand, where some require the base to adjust. This lets me take them to the bench for on-the-spot drop sets.

I workout every day and these dombells made my life so much easier. the only downside is pretty heavy when I put them away or move them around.

Does what it should.

There were a few reviews that stated their product arrived damaged w/ the styrofoam pulverized. Mine arrived in great shape with fully intact styrofoam, but I can see how 50# of hard metal can easily demolish the packaging if the delivery service isn't careful. The box was a little worse for wear, with the handles immediately tearing as soon as I tried to pick it up. Thankfully I saw the delivery guy on my door cam carrying the boxes (came in 2 separate boxes) individually in both hands; props to him. After unboxing and inspecting, the dumbells looked to be in immaculate shape. Switching between weights was easy and the locking mechanism showed no sign of getting stuck at any point. I used them in my first workout today and they felt fantastic! My only minor gripe is that when I pressed them overhead, the 2.5# bullets in the base of the handle made the weight feel a bit top-heavy, similar to trying to balance a kettlebell upside down (though nowhere near as unstable). Something to get used to, but definitely not a showstopper. Looking forward to getting stronger and adding on the Stage 2 & 3 expansions.