PetSafeDrinkwell Premium Pet Fountain Replacement Carbon Filters,Cat Water Fountain Filters, Contains 50% More Carbon (Pack of 12)

They fit and work well.

The filter helps the water stay fresh and clear of impurities for about two weeks at a time. I can tell it is working when I remove the old filter and there is a bit of a brown film on it. It's worth the money to keep my cat's water fresh and to keep me from having to change it more frequently. Very easy to place in the unit as well, and it fits perfectly in the allotted space and does not move around.

Ok, so I clean my Drinkwell Platinum Fountain Drinkwell Platinum Pet Fountain 168oz and put the unit back on the floor. I lay down on the coach to take a nap. Next thing I know I have 3 paws whacking me upside the head and I hear, "Hello Mcfly, you did not change the dang filter and now the water is running over the top of the filter." So I get up and check out the filter. Low and behold the cats were correct. I did not change the filter and the water just ran over the top and went to the basin without being filtered. Now this was the 5th time in 6 weeks I had cleaned the unit. Basically it took 5-6 weeks for the filter to clog up. As the 3 amigos stared at me like I was a complete idiot I proceeded to replace the old filter with a new one from my stock I had purchased on Amazon. Once the new filter was in place, the 3 amigos all took their turns playing in the water, only pausing to give me the look of, "next time don't be such a dingbat," then proceeding to continue their frolicking.So here is the skinny on the filters. They really don't consist of much other than a fibrous trapezoid shaped to fit in your Drinkwell filter slot. They do have a black carbon side with some carbon granules between both sides that is supposed to remove odor from the water. How much odor it takes out I cannot say. But I am sure it does help.These filters will not take out anything that would be considered harmful like hard metals or even any minerals. They are not made for that purpose. They are made to keep things like hair or food particles from recirculating. And they function quite well for that purpose.Length of life simply depends on how many cats you have, how fast the filtration flow is, and how dirty your cats are. Over time I have noticed that my usage, with 3 playful kittehs, varies between 4-6 weeks. Now one of my cats thinks he is a raccoon. He is constantly taking his food over the water and cleaning it. Ok, he may just be playing with it, but he does take it over to the Drinkwell unit and puts the food in the water and then proceeds to bat it around. I also have another cat that likes to use his paws to bring the water from the waterfall to his mouth. For these reasons I tend to get a lot of cat hair in my fountain. Most is stopped by the hard plastic "pre-filter" but some does get by. This likely has an effect on my filters lifespan.I highly recommend these filters. As I have yet to find a generic brand for these filters you really don't have much of an option, unless you want to make your own. I make my own fish tank filters, but I have a basket/case made for the filtration materials to fit in. I have never seen anything like that for these filters. For that reason you really do not have much option other than using these, unless you want to somehow create your own basket to put your filtration media into. That being said, these filters do what they are intended to do.Watch for these to be on sale in bulk. I have found a 12 month supply (12 filters/4 - 3 packs)Drinkwell Platinum Premium Filters, 12-Pack for a good price at different times. The price does fluctuate so you have to watch it. Sometimes it is cheaper to purchase them just 1 package at a time and sometimes it is better to purchase them in bulk.

I'm giving this a four-star revue instead of five because, although it seems to work well, I do not trust it (six-panel, grey filter) as much as I did the original product (single-panel, white filter), for two reasons.First, it continues to "shed" carbon for a long time, and all the nooks and crannies in my fountain are filled with a black deposit which is awkward to remove, even with Q-tips. If the deposit is only carbon, that's no cause for concern, but if it conceals food remnants that could cause health problems.Second, the filter doesn't seem to get dirty. My former filters would always show, by having visible food trapped on the upstream surface, that they needed changing. This model does not show food on the surface - which leads me to worry that the food is almost certainly entrapped, undetectable, within the filter material and decaying there. (And please don't respond by telling me that I need to change it every X days, whether it looks dirty or not - neither you nor I you have any way of predicting when one or several of my four cats will choose to dunk food in the fountain...)

Worth paying for vs. the off-brands I've tried. Nearly twice as thick as PetSafe, and slightly wider for proper fit. (Drinkwell Platinum fountain.)

Love the filters for my drinkwell fountian

Works great with my filter. Needs be run under water before you install it because stuff runs out of it for sure like some dust in the filter material. The box of packs last me probably like 3 months. Easy to change.

Fit and work just like the original filters that came with my Drinkwell water fountain.