Check this out. Some good explanations on how fins work and whyhttp://www.blackdiamondfins.at/en/fin-theory--all-about-fins
i had a look at them last night a very different shape,can you get any size you want or...?? the weed fins you can get a 20cm
Have some wee wee 120mm Fins that i've been working on for the last few months.
Be hard to find rocks with them 
