Product review (5 stars): Dont settle for only an NSF Type 42 filter!
Sure, you can find cheaper filters for your refrigerator,  most of those cheaper models are only NSF 42 certified.  Type 42 merely removes suspended contaminants to make the water look more pleasing.

In addition to NSF 42, this filter meets NSF 53 & 401 standards.  These additional standards help remove contaminants that cause health effects as well as chemical and pharmaceutical contaminants.

Spend the extra money and get a good water filter for your refrigerator.  I am very pleased with this one.

Ref:  http://www.nsf.org/consumer-resources/health-and-safety-tips/water-quality-treatment-tips/standards-for-water-treatment-systems