Oh, wow, these are great! As someone who's had a variety of exercise tools that have been little used, I can attest that these are ones I actually use and enjoy using. First of all, they're so comfortable in your hand or strapped to your ankle or arm. They're soft, flexible, made from excellent quality materials, and well designed. Even the velcro is the best I've ever seen. To create the kettlebell shape, you put the red and black side to the outside and run the strap through the handhold opening and slip it through the buckle, then press it to the velcro surface. You get a neat, sweet little kettlebell that's easy to pick up. As others have pointed out, this item can also be used other ways, including as a stretching tool, so you can make great use of the one set of kettlebells, and that prevents you from having to keep getting out additional equipment for other workout tasks. There are several advantages to these, one being that if you accidentally drop one on your foot, you're not going to have a broken bone. They're heavy--the sand inside them is iron sand--but they're not hard AND heavy like a regular kettlebell, which is made of cast iron. If you dropped a cast iron kettlebell on your foot, you would almost certainly have broken bones and a lot of pain. Another advantage is that because they're relatively small, you can just keep them all set up as kettlebells if you want and tuck them into a drawer, and they'll be ready to go whenever you are, whereas if you have real kettlebells you have to find a place to put them--probably not sitting out in your living room. Then there is the fact that although these are not cast iron kettlebells, you can still use regular kettlebell exercise videos with them. There's a good one for beginners on YouTube by chichihealthfitness that only takes 10 minutes and won't get you winded or sore, plus there are plenty more on the Internet for any level of fitness. For exercises where you're swinging the kettlebell, these soft ones are again safer, because a cast iron kettlebell can get a lot of momentum, and it can be hard to stop it before it hits some part of your body. I've had weights before that strap to the ankle or the wrist, and they did not compare with these. These are much more comfortable, and they stay where you put them, so they enhance your workout instead of getting in the way. I have medium-sized hands for a woman, and the handholds on these are big enough for me. However, as some reviewers have pointed out, the handholds may not be large enough for someone with larger hands. The opening on them compared to the opening on an iron kettlebell is considerably smaller, and an iron kettlebell's handhold stays permanently wide open. You may also have to reach more in exercises where you're passing the kettlebell from hand to hand around your body. That said, I would not part with these. I wasn't really sure if I would use them that much, based on my previous track record with various types of exercise equipment, most of which ended up being donated. I find these fun and easy to use, though, and like most women I really need some strength training, especially in my arms and hands. I think they're the perfect workout equipment to use for either regular or impromptu workouts. You don't need a machine, and you can use them anywhere--indoors, outdoors, or at the gym. As your workouts get easier, you can add more reps or lengthen the hold time, and if you like to work out to a video, you can switch out the videos you use too, so you can get a lot of mileage out of these. I just really think they're great.