Awesome fins! And they're not just for tech-divers.
First I'd like to clear up a misconception about these fins; that they are tech-fins. Now don't get me wrong, these ARE tech fins in the sense that if you are a technical diver these would be excellent fins to purchase. But these are NOT tech fins in the sense that you don't need to be a technical diver to use/enjoy them. Whether you're using a drysuit and doubles, or a wetsuit and a single tank (what I use), these fins are fantastic. First, the bad. The only truly negative thing I have to say about these fins is that they are made in Taiwan. They are very well-made, so I'm not trying to knock the build quality...I just wish they were made in the USA, France, Italy etc. like other fins I've owned. Also (this isn't really negative, but worth noting) if you are going to purchase these fins you should have good leg strength. You don't tree-trunk legs or anything like that, but these fins will be better appreciated by people who swim, run, ride a bike, etc. Now for the good: everything else! For frog-kicking, or modified frog-kicking these fins are wonderful; offering lots of propulsion with minimal effort. I was worried these would be more difficult/taxing to kick than my Mares Avanti Quattro's since they are heavier and stiffer, but frog-kicking is actually easier AND more powerful with the F1's. If you are using an up-down-up-down kicking-style these fins are excellent as well. I would say, overall, these fins seem more geared towards frog-kicks, but they are still good for up-down kicking and if you put some effort into your kick, you can move REALLY fast in these (currents=no problem). What I like about the F1's for up-down kicking is how smooth they feel. Part of this is because of the weight/stiffness/material, but part is due to the vents on the fin; the vents help the fin pass smoothly through water without the fin wanting to twist inward or outward. Another big selling-point for me is that these fins are very precise. If you want to turn, stop, rise, descent, rotate, invert, hover...you name it these fins can do it, and do it impressively well. The built-in spring strap is high-quality and the strap has multiple mounting positions to accommodate various sizes/types of boots. The foot pocket is very comfortable. The Mares Quattro is considered by many to have the most comfortable foot pocket of any fin. I would say that the F1 foot pocket is not quite as comfy, but it is pretty close and is overall one of the best foot pockets of the several fins I have tried. Overall I love these fins and would recommend them not just to tech divers, but do any diver who is looking for a high-quality, efficient, powerful, precise fin. Despite the fact that these fins are the heaviest I've owned, they are also the only ones I forget are on my feet...I don't have to think about my kicking because they are so intuitive to use. I own all my own SCUBA gear, but there are only a few items I own that I consider to be so good I would replace them an identical item should they be lost/broken/worn out, etc. The Hollis F1 is now one of those items. As a side-note the foot pocket is fairly big; I would say the \"true\" range for the size XL I own would be 11-13, not 10-12 (however, factory sizing is probably accurate if you're using drysuit boots).