ONEswim Rocket Boat Flotation Trainer

I teach over 1,000 swim lessons a year. I have pretty much every age , ability,and type of student. From babies, special needs, swim team, masters swimmers to triathlon swimmers. extremely active to very calm swimmers. I'm always looking for aids to help my swimmers. I was really excited to get this product and thought it would be more useful than a pool noodle which seems to always slip. The product did not keep any of my swimmers hips up , the product sank; even with my thin calm 3 year olds. It became dangerous with my average to Hyper swimmers as once their body weight shifted it became like a rocket and would launch up and hit whatever was in it's way with it's hard construction. only success I kind of had was with one of my small swim team swimmers who didn't need it and was calm.. I'm going to try to cover the hard body of it with a large, cut up pool noodle to see if it will then work to keep the hips up and be safe to use. great idea, made from the wrong materials, very wrong. Wish I could give it a good review. Sorry. . .