I have been using Everlast products for many years. Let me say I have always been satisfied with them. I recently purchased a 6''x9'' Sonic from Everlast and found the bag not to have a true bounce. I have been working a speed bag most every morning for many years. I can not seem to make this bag bounce. It is all over the place. I gave it some time to be broken in and have experimented with air pressure but nothing seems to work. So I guess that I am out of luck on this one. I use an Everlast 4''x6'' and have no problems with it even though it is faster than the new one. As far as I am concerned, someone dropped the ball on this one as far as quality and bounce is concerned.........hk