Alternative absorbent acoustic material?

The other posters are correct re: Owen’s Corning 703.

Of course, any mineral wool/rockwool that is high density is fine (i.e., Rockwool (100kg/m3 or higher).

The reason to use other materials is sometimes rockwool can absorb too much or you specifically want a frequency range to not be absorbed.

Or, more likely, you don’t want to work with rockwool, which is a PIA to deal with, mildly dangerous if you are an idiot, and can really make a mess.

Info from the company. 
https://www.owenscorning.com/en-us/insulation/products/700-series-fiberglas-insulation?utm_id=sem:nati:2024:search:1:1:700series:us&gad_source=1&gclid=CjwKCAjwxY-3BhAuEiwAu7Y6s2pR1g0z6VZql7XrOOIZ1Z2wpCj_fvntAjFAGs1DK-23s4apGariDhoCiS4QAvD_BwE

I heard a room at a shop that was extensively treated with Dow Corning fiberglass panels with Dow Corning supervising the design/installation.  This room, at a local audio store was intended to showcase such treatment.  The result, to my ears was odd sounding and too dry and dead sounding.  Musi9c was clear and detailed, but sort of lacking in liveliness and energy.  To me this was excessive damping, but, I have no idea what a lesser level of treatment would sound like.

In most rooms a combination of absorption and diffusion will result in the most pleasing acoustics. Too much absorption can result in a dead sounding room which is not pleasant to be in, let alone listen to music in. GIK website has lots of info. Their SlatFusors combine absorption and diffusion.

I went down this road recently and have done a fair amount of research on the subject but by no means am I an expert.  A few things I walked away with.  1.  It depends on the size of your room.  My room is pretty small, so it is recommended to trap as much Bass as you can.  2.  4" minimum is required to capture much base at all and it doesn't discriminate, so you need to use some sort of deflector so that it doesn't absorb all the mid and higher frequency (which is what makes your room sound dead 3.  there is very little difference between Rockwool, Fiberglass insulation and the different densities of those products.  

I made some 8' corner base traps using 2' x 4' x 7 1/2" that I found at Lowe's.  Generally the big box stores don't carry much in the 2' wide size.  It's usually the 15.25" x 3 1/2" size which fits between standard wall studs which is a little shy on what you need for depth.  I opted to be that from ATS as mentioned above.