From 2004 to 2007 the M4 was a favorite with surfers on tour for riding small to medium waves: Flat entry rocker, increased tail kick, full rail, and single concave. The M-4 has a wider nose and tail, so ride this one an inch shorter and a hair wider if you surf mostly in small waves. The M-4 is considered one of the more forgiving boards in the CI line. The M4 is still a popular board for custom orders.