For anyone looking at RO systems, I recommend the APEC brand. Their hook is "assembled in USA" (meh, import parts) but I'm more impressed with the build quality. Three
BIG pre-filters (one sediment, two charcoal), a substantial RO membrane, and a carbon post-filter. Materials are heavy and of good quality. It also has a full-sized holding tank rather than the chintzy 1.5 gallon unit I see on most Big Box store offerings (I can fill two gallon jugs and still have enough to make a pot of coffee).
I've had one at my place for a year. Zero problems. Installed the same unit for SWMBO a few months back. No problems there, either. Both installs are under-sink. The only caution I can give is that the unit is larger than what you can get from Big Box, both in filter assembly and tank. Plan space needs accordingly. Also, familiarize yourself with push-type fittings. It's easy to not get the tubing seated properly in the fitting. That's bad.
I got mine from Amazon. Price isn't much more than Big Box stuff and the quality is far superior.
https://www.amazon.com/gp/product/B00I0ZGOZM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1Pre-filter replacement cartridges run $30 a set.
https://www.amazon.com/APEC-Water-Systems-FILTER-SET-ES-Filter-Set-Es/dp/B00I11HUGW/ref=sr_1_3?keywords=Filter-set-es&qid=1563810645&s=hi&sr=1-3Full replacement filter/membrane set is $75.
https://www.amazon.com/gp/product/B00I5WSO8A/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1The filter assembly comes pre-plumbed. All you have to do is hook up the water supply, set up the tank, and plumb in the drain. Everything is included, though I replaced the cheapy needle valves with quarter-turn units set up for push fittings. I also added discrete shutoffs for the ice maker and RO spigot. On mine, it also gave me the opportunity to toss the old PITA hard lines and put in hoses. I used a brass tee on the main valve so I have discrete, separately-valved supply lines for the faucet and RO system.
Brad