6" duct muffler

Okay, I've got another post - "Acoustic Duct" - in this forum, but I'm not having much luck finding it (USA). Plenty of insulated duct, but no acoustic in 6".

So - has anyone used this item:

http://cgi.ebay.com/6-DUCT-MUFFLER-FAN-CAN-SILENCER-NOISE-REDUCER-inch-SIX-/120732954948?pt=LH_DefaultDomain_0&hash=item1c1c3eb144

It's from HTG, so I know they have a good rep here. But if you have used this specific item, please let me know how well it did (or didn't) work.

I need the sound to be super quiet. The hookup will be - carbon filter/6" fan/ a 90 degree elbow/ some flex duct/the muffler/out the vent into the room.

Thanks.

Quite honestly, HTG has very low quality equipment. For the same price, you can get a Phat Duct Muffler from Greners.com, which is really the best muffler on the market. Go with this, and you won't be disappointed.

I'll look into that, thanks.