Specs. The ATS doesn't specify the depth, but it links to the 2inch product:
Product Name Density
lbs/ft3 125 Hz. 500 Hz. 1000 Hz. 4000 Hz. NRC Rigidity Price/sq.ft.
ATS Acoustics Rigid Fiberglass Board 3 lb. 0.29 1.11 1.131.03 1.00 Rigid $1.23 Plus: An exact substitute for 703 at a better price. Minus: A little more expensive than AFB and Rockboard 60 for the same sound absorption.
Owens-Corning 703 2" 3 lb. 0.17 1.14 1.07 0.98 1.00 Rigid $1.54 Plus: Well known product. Good for small projects where cost is not a big concern. Minus: More expensive than AFB and Rockboard 60 for the same sound absorption.
The front wall of my new studio will be a "V" shape with a depth of 16" on the sides going down to 4" in the middle; apx 11ft wide and 8ft tall. It will be 4" deep 703 (or ATS) via two 2" panels glued together on the edges and the middle 7ft + will be 2" deep. Behind the 703 will be fluffy fiberglass for the cavity. The ATS stuff seems to spec out pretty close, but obviously the specs for this stuff doesn't really tell the whole story as none of it was ever designed for acoustics. With all the other stuff I need to do to the space, I've got to pinch some pennies here and there, and this will save me a few bucks.
FWIW - There will be other bass trapping in the studio. Essentially a the wall/ceiling corners around the rest of the room. These will be 6" 703 straddling the corners with air behind (recycling what will be my old free-standing 6" deep bass traps for this purpose, which were OC703). The rest of the room will have varying absorption and diffusion.
So I'm just looking for someone with firsthand experience with both.
Just talked with someone at ATS. They can't tell me who the manufacturer is (no suprise there), but she said she could see if they have a spec sheet from the manufacturer with more info she can fax me with the name blanked out.
She said she's used both and she said the rigidity is pretty close and you can wrap them in fabric like you can with 703. she said that if you lean up against the ATS it will hold the compression shape longer than 703 before it comes back. She confirmed that the specs on the site are for the 2" depth and that it is in fact 3lb density like 703.