I've used these units for about 10 years, been happy with them and water tested after the unit has always been good. Filters and a push button quick connect which makes changing them a breeze.
https://www.premierh2o.com/531411-ro-pure-guide
I have a friend who had a very similar looking saw (I forget the model #) it didn't have a valve for down feed pressure. It had some spring assist that didnt work well, was great for ripping teeth of the band if you didn't baby sit it.