Cold and humid days can be hard on a standard glow plug. Weather conditions like these can make a normally superb plug idle rough or load up in the mid-range. Even a great glow plug like the race-winning Dynamite MC9 can have trouble on this kind of day. No worries, the new MC59 glow plug has a hotter heat range, giving great performance in cold or wet conditions. Racers serious about competition will always have both MC9s and MC59s in their pit box to match race day conditions. Be prepared and be a winner! These move FAST and are hard to keep in stock!! Keeping checking back on these!!