but according to the costco link and screenshot below it is written as 10".
https://www.costco.com/Bose-SoundTouch-Soundbar-System.product.100386046.html
Please clarify
Hey syedfirdaus,
Thank you for the post. The Compact Acoustimass module for the Costco system is 10" wide and 10" deep, which is what the 10" on the site is referring to. The Compact Acoustimass does have a 5.25" woofer. The full size Acoustimass 300 is larger in dimensions and does contain the larger 10" woofer. I hope this helps clarify. Our apologies for the confusion. Please let us know if you have any other questions!
Kind Regards
Brent - Bose Support
I bought the Bose Sountouch 300 at Costco. From day one the subwoofer sounded kind of "bad," almost like it would struggle. Out of curiosity I stumbled across this thread. This thread made me order the AM300 to see if there was a difference. BOY, what a difference it made. The difference was night and day. There is no way Costco should be selling the crap "special" sub and soundbar for $999.00. It should be included for "free" at $699.00. Seriously, it sounds REALLY bad, mostly discernable when listening to music. Bose should even be ashamned to manufacture such an item. Anyone considering the SountTouch 300 should get the real subwoofer and steer clear of the Costco variant. Mine went back to Costco. I've never been really disappointed in a Bose product, but the small sub at Costco (which wears the Bose name) definately disappointed me.
Are you able to pair the rear VI surround speakers to this Costco package?
Yes.
...and if you do, please report back to the Community your findings. Others who have yet to Google the Costco variant are likely to run across your posting and would probably really appreciate your thoughts.
Yes, the bass response on the Bose Costco Subwoofer is not as strong as the AM300 BUT it is perfect for streaming and DVD movies. For music I use my Grado headphones or Bose 25s anyway. I have hearing aids and for the first time I can understand speech and the Costco subwoofer contributes to that. Thanks 
Try boosting the bass on the remote. It helps.
I just purchased the soundbar/woofer at CostCo. I also purchased two soundtouch 10 speakers. My goal is to have them all paired and synced to play theater sound with my smart TV. How do I do this ??? Any help is appreciated
Unplug both the sound bar and speakers for 30 seconds. Plug back in Andre if the speakers lights turn from amber to white. Recalibrate from several locations. You should be able to use your app to turn on both the speakers and the soundbar at the same time.
