Love these fins, I got them used for $80 Only had a few scuff marks on them That I was able to get off easy. you definitely need booties With these Fins but after that they are glorious I move through the water so fast I leave a wake behind me. I am very muscular legs I would imagine if I didn’t these would be difficult To use just a heads upReally like these fins. They are a vast improvement over my old split fins. Good power, easy to get on and off. Would buy againGreat thrust, need acclimation to be strong to handle theseThese are amazing fins. I tried going back to my old fins after wearing these, and simply couldn’t.These fins are so powerful. I have lots of control, and can go fast. Also great for building leg and glute muscles.Downside is that they are heavy and take up a lot of room in the sports/dive bag.But it’s worth it.Meant for diving , these few fins worked great for snorkeling too.Love the bootie, great for clamoring over sharp rocks / sea urchins !As a tech diver I am always on the lookout for high durability and performance for all my scuba gear in general. These fins make a great addition. They are on the larger side thus a bit more effort needed to use them but you'll get great speed out of them.Note - they are a bit on the heavier side due to their size and material.I wear a mens US size 7.5 generally. I went with a size 7 Mares Flex DS 5mm boot and chose the size small fin based on the chart and not going up a size to accommodate the boot. Just fit! Boot slides in and leaves 1inch hang. Foot in the boot, it hits the sides of the cup just to qualify as a snug fit towards ankle while leaving toe wiggle room in the box. If I had moved to a regular it would have been sloppy loose. Fins came with strap extenders to help if strap feels tight. If you have super thick boots or an incredibly wide foot... Go with the regular. Side note.. I def got a pair of returns. They are in great condition so I'm not mad and understand people try them and return them. Consumers.. be kind, put the parts back in the little baggie, don't tear up the warranty and info cards and stop stealing the sticker!I had been using Atomic split fins for a long time. I was looking for more power with these blade fins. First of all, bungee straps or spring straps are a must. I wear a size 11-11.5 for shoe size and the xl fit perfectly. For flutter kicking these fins are a little rigid. I just got them so I imagine they will loosen up. For frog kicking they're just fine. I only gave them four stars because of their rigidity, but, like I said, they'll probably loosen up a bit. Decent fins for the money.I’m a very experienced scuba diver and afternoon trying many fin types I have finally settled on Avanti Quattros as my favourites. The level of precision and control you get from these is second to none, I can turn on a dime with a subtle ankle flick, the ridges make it feel like I have fingers on the end of my fins. When you want to go quick the power is there, when finning hard the fin is Very heavy but offers huge power.The only downside is the size, they’re enormous! They can be annoying to pack. Oh and the replacement bungee straps are heinously priced.By far the best fins I have tried. I have very small feet for am adult (UK 2.5-3 ) the small size fins in this make is recommended for boot size 4-5 UK, so I was really worried that may rattle or even worse, come off in the water... I didn't need to worry as they are just perfect. It's amazing how much impact a pair of good fins has on air consumption efficiency. Before these fins I used to go through 150 bar in about 40 mins at average 23 meter depth. With these Fins I managed to reduce my air consumption by about 50%...Love these but after only 20 dives the ‘nub’ on one fin for one of the bungees has distorted and it keeps popping off. Apparently Mares are aware of this issue but not actively replacing affected fins.I love mares a avanti Quattro plus fins best all rounder on the market I’ve had several pairs over the years and wouldn’t use any thing else the new ones are even better than the old model and still a good priceGreat pair of fins, comfortable and so easy to get on and off with an extra little loop for your finger to make sure to don't lose them in the process. Great fins, would recommend.