The mast base engages the mast ball and is secured by this headless clevis pin to allow the mast to be safely raised or lowered. The pin measures 1/4" diameter x 2-3/8" overall length with a grip length of 1-15/16". Fits Nacra 4.5/450, 5.0, 5.2, 5.5SL, 5.7, 5.8NA, 6.0NA, 5.5UNI and 18SQ, as well as Hobie® 17 and 20. Split rings are sold separately. This item is substituted for Hobie Cat® #50406301.