LBX4/LBX 3.8 quad combo composite fins for use in the Lokbox fin system. 50% glass-filled nylon molded composite fins that are very full foiled from base to tip. The result is a much stiffer, snappier feel over traditional composite fins LBX4 Base: 4 1/2" or 114 mm. Height: 4 5/8" or 117 mm. Ideal Weight: 140+ lbs or 63+ kgs. Timmy Patterson template. Performance fin with power and drive for the medium size surfer. Larger base and fuller tip makes this fin good for bigger powerful surfers. LBXM 3.8 Base: 3 5/8" or 92mm. Height: 3 7/8" or 98.4mm. A high performance quad rear fin with a 80/20 inside foil. Can also be used as a longboard side bite