I don't consider myself a professional, but you need previous monofin experience before purchasing this product. I have used this product consistently for 4 months. I have been using the finis rapid for a couple of years & was ready to graduate up to something more professionally made. This fin will seem large & heavy, but i believe it will last a long time. I wear womens 10, men's 8.5. I ordered a large (teal foot pocket) & am happy with the fit. However at first i felt it lacked ankle support; now i am totally capable of not using my ankles or knees. you will NEED to order a type or neoprene fin sock. I started by using thick sport socks, but still blistered badly. But the fin is comfortable for long periods of time with a proper neoprene sock. I comfortably swim 10 laps per 15mins. I am also a female weight lifter & lift 5 times a week. I swim 25-40 laps in this monofin 1-2 times a week for my cardio. This style of cardio is amazing if you suffer from knee pain, like i do. Using a monofin is a great workout for your back, core & stamina because it can knock the wind out of you real quick. My point being, i do not believe i could properly use this, if i was not lifting & lacked the strength, especially in my back. I would not buy this for children. But if you're serious about fitness & you have a passion for swimming or the dolphin kick, this may be the right product for you.