Product review (3 stars): Scary but it works. Read this about fit issues other reviewers are posting.
OK, folks. Here's the cheese. There are many negative reviews for this product stating that it doesn't fit, even though they ordered the same part number as before, etc. I have shared this experience, but I got it to work. Here's what happened.

We have a Samsung RSG257AARS refrigerator, 2012 manufacturing date. All along I've been putting in the original Samsung DA29-00003G replacement filters, or the HDX equivalent FMS-1 from Home Depot. We were due for a replacement so I ordered this three-pack of the Samsung original part. When I went to replace the filter, I couldn't get it to fit. First, it didn't seem to line up properly with the lock marks on the receiver. To get the filter to seat in the receiver, it had to be 1/4 off the "unlock" mark on the receiver. Then, it wouldn't turn. Tried again. No really. Wouldn't turn. OK, let's clear the top shelf, remove the shelf, and really reach in and give it some more welly. Two hands and the filter and it would not turn. Check the part number on filter. Check the web, make sure I really ordered the right filter for this fridge. Check the box. Check the filter again. Noticed the "tooth" pattern on the filter is different at the top (three teeth vs two on the old filter). The center hole diameter is also different. Uh oh. Maybe mislabeled product? Check the box again. All seems right. I have some food-safe silicone lube that I use on the o-rings of other filters in the house, so I applied some to the filter and tried again. No joy. What the heck is going on?

So I got on the phone with Samsung, and here's what I was told: first, the design of the filter has changed. I commented on the fact that the part number didn't change, and he just said that's what the engineers sometimes do. After confirming I had the right part numbers for the model and serial number on the fridge, he told me that it will fit, it just takes considerable force. Really? Well, OK. I put the phone on speaker and set it down, and prepared myself for a shower. With two hands on the filter, I pushed up and turned with more force than I was comfortable with. No joy. When I told the Samsung rep it didn't work, he said they know it's really difficult, but try again. OK. Here I go. I hauled off on that thing, full expecting to snap the receiver off the back wall of the fridge and have water spraying everywhere.... and it turned! It turned and locked in, and I could hear water flowing into it. Check for leaks. No leaks. The "lock" icon on the filter is even correctly aligned with the mark on the receiver. Wow. For real, it works.

That's it. They changed the design of the filter, and didn't change the part number, and the new design takes A LOT of force, more than you used to use, and probably more than most people are comfortable with. In fact, I don't think my wife would have the hand strength to do it. But force applied, it does work. I'll add that with the amount of force it took, I'm glad it still had some of the silicone lube on it that I had applied in my earlier attempts, because getting the thing off could be interesting. I'll know in six months or so.

Short version: part number changed. Get it seated, then applied a LOT of upward and twisting force to the right. It will go on. You will be scared the first time. You will wonder why they changed it and made it this way. Consider pulling the fridge out and turning off the water before you do this.