Cheap RO/DI Unit

If a vendor does not tell you the specifications on the carbon blocks you can bet they are trying to pull the wool over your eyes. Same with the sediment filter, does it mention nominal or absolute rated?

Then you need to understand RO membranes, they say 100 GPD and down to 0.001 microns? That dooes not meet drinking water quality standards in the USA. A good membrane like the Dow Filmtec or the Spectrapure that starts out as a Dow before they treat and test them is rated at 75 GPD at 50 psi or 90 GPD at 60 psi and at 0.0001 microns, 10 times more efficient and they do meet ANSI/NSF standards for drinking water use.

The ebay vendors use tricky or deceptive language and you have to read between the lines and ask questions.

You wil probably also find it uses cheap compression fittings that leak versus john guest style speed fittings, probably uses no name housings and sumps that eventually leak due to inferior plastics and are not NSF rated etc. Ask lots of questions and make sure you are getting what you think you are getting. Without even seeing it or knowing the brand, I can just about guarantee money you are not. Spend you hard earned money wisely. There really is a difference and cheap is for a reason, or reasons.