I'd probably be better off spending my time learning why Monster Cables are better than all the rest. 
 
 
 
 
There are two things a studious person will want to know about that product, but the website doesn't have the info available.
 
1) How many pounds does each blanket weigh? If they tell you what it weighs you can compare it to other blankets that are made out of the same cotton and wool stuffing and figure out how much each choice costs per pound.
 
2) Where is a list of absorption coefficients at 125Hz, 250Hz, 500Hz, 1000Hz, 200Hz, and 4000Hz. A NRC rating of 0.65 is a meaningless figure.
 
 
 
 
 
Studying absorption characteristics is fairly basic stuff. Blankets do absorb sound. In general, the heavier they are the more they absorb. In general, the more complex the fiber stuffing is the more they absorb sound. In general, the thickness of the material will coincide with the item's effectiveness at absorbing lower frequencies.  
 
One thing to keep in mind is that it is very easy to hear how a blanket deadens mid range and treble frequencies, but the frequencies that most often need to be deadened are the ones that pass right through the blanket. The point is that it is easy to make a room sound dead but not necessarily nice. 
 
Bob Golds has gone to the trouble of posting some detailed absorption info where you can see what frequencies are most often absorbed by various materials:
 
http://www.bobgolds.com/AbsorptionCoefficients.htm
 
 
A wonderful tidbit of wisdom can be found in the middle of Bob Olhssons' webpage:
 
"One thing that makes a room sound good is a reasonably flat reflected frequency response. When you treat a room, it’s really easy to have a lot less top-end and mids coming back than lower mids."
 
There is a lot of easily accessible info available for anyone who wants to study.
 
I think the most important thing is to maintain a focus towards determining which frequencies need treatment and which solutions will help you further that goal.
 
 
best regards,
mike

I’m not sure if purchasing based strictly on a price per pound basis is the best approach.  If the cotton-wool blend is truly acting as an absorber then the density at which the fibers are packed will affect the efficiency at which the acoustic energy is converted to heat energy.
 
Edit ... not sure if efficiency is the best choice of words but you get my point

Yes, I agree.

This table from Bob Golds web page illustrates the bell curve of how a materials effectiveness at low frequencies seems related to density:
 
                                                                125    250    500    1000  2000  4000  NRC
701, plain 4" (102mm) on wall 1.5 pcf  0.73   1.29   1.22   1.06   1.00   0.97   1.15
703, plain 4" (102mm) on wall 3.0 pcf  0.84   1.24   1.24   1.08   1.00   0.97   1.15
705, plain 4" (102mm) on wall 6.0 pcf  0.75   1.19   1.17   1.05   0.97   0.98   1.10
 
Blankets are usually somewhere between 1 and 3 pcf so unless you are squeezing them flat you will not pass the threshold of diminishing returns by seeking out the heaviest examples you can find.
 
best regards,
mike 
 
 
edit table formatting

i'm just trying to help mike.
 
i don't know about all the science
 
and frankly, i do not care.
 
i DO know, that i have used regular blankets, wool and cotton....
some have been heavy, some light weight.
 
i also know that i have used movers blankets.
 
and that this product (which i actively use) works much better than any of the above.
 
 
that is all.
 

http://www.audimutesoundp...sorbtion-material.aspx

You're right about moving blankets; for general acoustic treatment they're next to useless. I was actually making a joke referring to U-Haul blankets. They are, however, handy for draping over a kick drum or a guitar amp.
 
I was also making a perhaps too-subtle joke about the claim that Audimute blankets are as effective as acoustical foam. Acoustical foam isn't very effective. But if it meets your requirements, the Audimute products are less-expensive than Auralex foam.
 
Mike's point is that rigid fiberglass is a more efficient absorber at the frequencies that matter. It's also cheaper than any other equally-capable material.

"cheaper than any other equally-capable material."
 
This made me wonder... I wonder how much this would cost?
 

 
Maybe I can find a close out sale somewhere.

 
 

op said sound dampening.