North Extender

Some North sails mast specs use a Carbon Extender.
This refers to a fixed extension which is designed to increase the mast length and stiffness of North's small masts for bigger sails.It is a fixed carbon mast extension of that still allows you to use a standard mast extension, and has no effect on mast durability when used with the North masts.

Silver Xtender 40cm 55%Carbon available for Standard or Reduced diameter masts
Platinum Xtender 40cm 100%Carbon available for Standard and Reduced diameter masts