Futures JJF XS Grom Thruster FinsThe John John Grom model is an xtra small size Balanced fin with a Ride Number of 6. 1. This fin is a re issue of JJF's Signature Skull model from 2008, back when he had his long hair and only weighed a hundred pounds. The template is upright with a refined tip, providing a loose feel for the kids. The Honeycomb materials make it lightweight with a neutral flex pattern, resulting in a great all around ride for the next generation. Template Category