These fin screws make so much sense because you can adjust your fin in the water. One thing I hate is having to get out of good surf to change fin position with a screwdriver; I got some of these so I don't have to worry about that anymore. Bag of 3 screws with plates for $6.95 and "OFF10" for 10% off. Since you're getting a discount, you might as well buy one of the "Pintail" flex fins as well; unlike the similarly-outlined Velzy which has little flex, the Dorsal is flexy without being floppy; excellent projection out of turns and it's surprisingly inexpensive ($27.40?!?) because they're molded polycarbonate. I'd never used anything but fiberglass, but gave this a go last month in my heavy 11 foot TMartin Legacy that has a similar outline to your board rootdown and it worked great. I also got one of the astroturf mats that's very similar to ones Tico used to make. The Dorsal mats are excellent. Very heavy duty; sturdily made and the astroturf is nice and soft. It beats gravelly asphalt--with the occasional little bits of glass--any day of the week. https://www.dorsalfins.com/collecti...screw-an-plate-surfboard-longboard-sup-bag-of https://www.dorsalfins.com/collections/dorsal-pintail-fin The base is wider than the box opening but sits snugly on top of the box which adds rigidity to the fin, complementing the flexy leg. And yes that crusty, oxidized fin screw was replaced with the new, tool-free one.