Product review (4 stars): Not quite the same measurements as the LG version
It does fit and works as a replacement for the OEM filter, but the measurements are slightly different.
LG: 12 3/16" long, 59.1mm diameter
Swift Green: 12 7/16" long, 51.7mm diameter

So the Swift Green is 1/4" longer and 7.4mm (just over 1/4") narrower than the LG.  Due to the smaller diameter it will look like the filter is too small and won't fit properly when you go to put it in.  Don't worry, it fits, there will just be some space around the filter due to the smaller diameter.  It will also take a few seconds to get the inner portion of the filter to line up properly to lock it into place.  Once locked in place, it doesn't move and is just fine.

My refrigerator is the LG LMX21981ST.  It is a counter depth model, so it is shallower than normal.  It also has the water and ice maker on the door which take up some of the interior room.  All of that combines to mean there is very little space between the filter and the ice maker door when the refrigerator door is closed.  The extra length of the Swift Green fits, but it sticks out far enough to hit the ice machine door.  I only found out because the main refrigerator doors were making a different sound than normal when they closed and I wanted to find out why.

If you're wondering to yourself if your refrigerator is counter depth or not then it probably isn't.  I found out when buying mine that even though counter depth units are smaller, because fewer are built and sold they actually cost more.  Annoying.

From the box, these are the specifications:
Max operating temp: 38C/100F
Min operating temp: 0.6C/33F
Max working pressure: 689 kPa/100 psi
Min working pressing: 140 kPa/20 psi
Rated capacity: 2,271 litres/600 gallons  (LG filter is rated for 300 gallons)
Flow rate: 1.9 lpm/0.5 gpm
Estimated % reduction:
Lead - 95%
Cysts - 99%
Chlorine taste & odor - 95%
Turbidity - 95%
Asbestos - 95%
Atrazine - 95%
Alachlor - 95%
Lindane - 95%
2,4-D - 95%
Mercury - 95%
Toxaphene - 95%
P-Dichlorobenzene - 95%
Benzene - 95%

It also says it keeps a healthy level of fluoride in the water from fluoridated municipal tap water.

Last, when you go to replace this filter there will be a bit more water leakage from the filter when you remove it.  It doesn't lock water inside the filter to quite the same degree as the LG filter.  If you normally use a towel to catch the drips during a filter change, at the very least double up the towel.  A paper towel alone won't suffice.  If the area is free, you could also use a bowl or cup to catch the water and then just wipe up the remainder after it finishes draining.  Would definitely be easier.

If you have a counter depth refrigerator with the ice maker on the door, I recommend sticking with the OEM filter.  If not, I can't think of any reason why you shouldn't try this filter.