These double-packs are the best deal going for whole house filtering when your needs aren't met by a prepackaged unit. Some plumbing is required of course, so you must be more willing to get your hands a little dirty. I did have an issue however - wall mounting brackets. Based on the question/answer section, these housings were supposed to take mounting brackets with the "standard" 3 inch x 3 inch hole pattern. The housings I received DID NOT - the hole pattern was 3 inches wide by 2.75 inches deep, so the "standard" brackets I ordered separately did NOT fit. I don't know if I got older models where they weren't standard, or if it's the newer models that are not standard - in any case I was stuck, and to top it off I waited way too long (6 months) to attempt the install so I was unable to do any returns. In desperation I called up iSpring directly trying to figure out what mounting brackets I needed. My call was answered by Nick (a very helpful and friendly fellow), and I explained the situation. He was surprised that the items didn't come with mounting brackets (which was news to me reading through the previous reviews). So after I supplied him with pictures of my problem and my receipt from the purchase, he shipped me the brackets for these filters the next day. Can't beat that customer service, and I'll certainly be returning to iSpring for my water filtering needs in the future. Thanks Nick!