Product review (2 stars): Not A Good Fit!  Beware...
This replacement air filter was just slightly longer than the original Whirlpool refrigerator air filter it replaced.  While I was able to insert this filter into the designated slot on the rear wall of the refrigerator, the filter did not "easily snap into place" as the instructions stated.  In fact, the opposite was true:  I was very concerned about forcing the slightly over-sized filter completely into the slot and not being able to readily depress the side tabs and remove the filter without damaging the refrigerator. Therefore, I carefully pushed the air filter into the slot but left it protruding just a bit so I can still access and depress the side tabs of the filter to remove it later (hopefully without too much trouble).

Apart from not having a flush fit (which causes the air filter door to very slightly stick out), another irritation was the lack of a time strip.  The original Whirlpool refrigerator air filter came with a small gray, triangular shaped time strip which is placed to the left of the air filter before closing the small vented door where the air filter is located.  Depressing a small "button" on the rear strip causes it to start a six-month countdown indicated by a very slowly moving red bar which can be seen when the vented door is closed.  That red bar reaches the end of the strip after about six months and serves as a visual reminder to change the air filter.  The Tier 1 replacement air filter does come with this time strip.

Overall, this was a cheap but disappointing purchase.  It was not worth the time and effort to return this item.  Next time, I'll pay more money to buy an original Whirlpool air filter.