Unfortunately as this industry grows there are more and more companies trying to bank a quick buck.

The product NT-FR 2000 is not a 20 vapor barrier, unless you care how thick it is at the string reinforcement. If you measure the barrier at the string (which sticks up from the barrier) it may measure 20 Mil only because there are 2 layers of string, which makes it a 5 ply.
The DrySpace™ brand crawl space vapor barrier measures almost 24 Mil at the string reinforcement, but that does not matter to us. The vapor protection is in the thickness of the polyethylene; the string is only for additional strength and plays not part in moisture control. This deception is true with their NT-1600 and NT-1200 as well, take a look at the table below or click here --> 20 Mil vapor barrier to see the 20 Mil comparison.

Fire Retardant

Fire retardant is an additive put into the polyethylene to suppress flame spread. The first thing we need to understand is everything on earth will burn and polyethylene is no different. When a fire retardant is added to a vapor barrier the goal is to have the plastic extinguish on its own when the flame source is removed. For every action there is an equal and opposite reaction; The more fire retardant that is added the more smoke there is once the flame goes out. That is why the tests are designed to measure both flame spread and smoke development. The closer the product gets to a 0 flame spread, generally the higher the smoke development and the lower the smoke development the higher the flame spread. As you can see it takes trial and error to get a acceptable level of both. The manufacture did not design this product to be used in crawl spaces; it was designed for equipment storage, landfill covers, athletic field covers, crop protection etc. So you can see why it is far more important for this product to have a strong flame control than it is to have a strong smoke control with these types of outdoor uses. This product has a flame spread of 5 and smoke development of 80, which less than 50 is required for most building codes.
We can get this product for you at a better price if you feel it fits your needs better.
The company that renamed these products, NT-FR 2000, NT-1600, and NT-1200 buys them and then resells it. They mark up the real thickness, and then mark up the price to compete with our products and give free shipping. We are offering free shipping in February on all orders over $250 and we will do the same with this product. Please call our office to order if you wish to use this product in your crawl space instead of the DrySpace™ brand. I am certain we can get you a much better price as well as extend our expertise to help you get it installed.

The easiest way to know what you’re getting is by finding out what it weighs!

When it comes to the phrase "light weight heavy duty material", well there is no such thing. It's either light weight or heavy duty; they are two completely different classes. This term is used by this company to describe their products, probably to assure you that it is strong but not very heavy. With a material like polyethylene there is not much difference in weight, only depending on how much high density and low density polyethylene is used to make the barrier. All vapor barriers are weighed per 1000 square feet and that weight does not vary much more than one or two pounds. In the case of the NT-FR 2000 it weighs 74 pounds per 1000, when a real 20 Mil will weigh in at around 105. So if you see two polyethylene barriers one weighing even 10 pounds less, that is a signal that it has less polyethylene in it and therefore not as thick. Take a look at the other weight differences on the tables below to see what I mean. Oh, one more thing- all of these numbers were taken from the other company's site so they are accurate. Also know that their business is selling water and furnace filters not fixing crawl spaces.