I purchased the Everlast Cardio strike bag a few months ago from Costco online. It was a great price and even came with neoprene gloves. I wasn't exactly sure how the bag worked but figured I would give it a try. I was disappointed when it arrived to find out it was a "blow up" bag. I had concerns about how well it would stand up to punching but decided to put it together. The assembly was really easy although filling the base with sand proved to be a bit of a challenge. I used almost two 25kg bags to fill it but that was plenty. The bag was on a spring so you couldn't have a continuous punch, you had to wait for it to rebound back up. This was okay, you just needed to get into a rhythm with it. I only used the bag a handful of time when the inner bag popped. Thank goodness for Costco's return policy! I don't recommend this product at all, spend a little extra and get a proper free standing bag.