GLACIER FRESHReplacement Filter for Maximum Under Sink System, Compatible with 4US-MAXL-S01 System,2Packs

Do they work, yes. Does the water taste better, well yes. But do they actually filter according to their specifications, I don't know. I looked on the box description and they said it does everything that the Filtrete filters do but there wasn't any link in the product description to a known, trusted organization where the test results of the filtering action are published. Since there is no other alternative due to low supply from Covid-19 from Filtrete we are stuck with a third party with no affiliation to a testing facility to prove its claims unless Glacier can provide that information.Note added 8/16/21: Caution! High water pressure from provider could cause these filter to stop working. If filter experiences a brief "shuttering" noise before flow stops it is the water pressure. Stop supply, remove, drain, and slowly open valve to a pressure the filter can handle. It took me two tries to get correct pressure. However now flow is a little less & I don't know if its the pressure or if filter is damaged.

With the pandemic, Filtrete (3M) discontinued production of the 4us-maxl-f01 filters, so we were at a loss until this came up in our search. It's been installed about 2 months, fits great, and seems to do a good job. Is it as good as the OEM filter? I can't be sure, but it seems sufficient.

3M/Filtrete folks have not been making the 4US-MAXL-S01 for over a year. I called them and they could not give me a date that they might start back up production. This replacement filter says that it filters out the same contaminants as the the Filtrete one. The taste is fine and the cost is 1/2 of what the 'old' Filtrete one cost so I'm going to use these from now on.

I have yucky tap water. This filter works great for a month or so, then the yucky taste starts coming through. With the 3M filters I get around 3-4 months. Also this filter is not NSF certified.These filters are a great option if you can't find the original 3M ones. Just buy a few extra and change them more often.

Water flowed great the first day but the second day it was just a trickle. This never happened with the Filtrete brand filters that I can no longer obtain. I just switched to Insinkerator’s F2000 filter (super easy to switch the permanent connector to the existing water lines) and the flow has never been better. Avoid Glacier’s filter.