Most are all the same. Sediment filter, chlorine block filter, membrane, and a Di resin chamber.
Some have extra filters or resin chambers, double membranes, and built in Tds meters.
Imo, get a 75 gpd unit as thats the most common size for replacement membranes.
There is only a couple of membrane manufacturers, and they just get re-labeled for use.
Check out prices from the vendors here before u buy.
If it doesn't have a built in Tds, them make sure to get a handheld one as that is a necessity with an RO/Di.
TB aquatic is a vendor here and has great prices on replacement filter packages.
Sent from my ADR6300 using Tapatalk