The Lovelace FM Twinzer set was specifically designed to be paired with Ryan's FM board model. The front nubs have a single foil with a flat inside, while the rear twin design features a double 50/50 foil. This unique set will provide lots of speed, drive, and the ability for heavy rail carves and fluid arcing turns when paired with the proper board. Here are some more design notes from Ryan...

"These fins were designed specifically for the pretty oddball placement of my FM surfboard design; over 2" off the rail on mid lengths and nearly parallel; either with or without the leading fin depending on the rider's preference.  The overall template plus the fact that they're double foiled aims them pretty definitely at midlength twin designs, drawing connected, arcing carves.

There is considerably more surface area on this template than most average twins.  So if using them in an alternate surfboard than the 'FM' model they were designed in conjunction with, I would suggest they be used either in midlength twins, by larger surfers on 6' range twins, or surfers who really like to weight the rail and load up drive.  

Alternately, the Piggyback keel is a very similar template and at a smaller size more suited to 'normal' sized twins." 

( Front Fins )
HEIGHT: 1.63" / 42.5 mm  
BASE: 3.33" / 84.5 mm
AREA: 3.70”² / 23.87 cm²

( Back Fins )
HEIGHT: 5.60" / 142 mm  
BASE: 4.65" / 118 mm
AREA: 23.12”² / 149.16 cm²