Making a bat that is light enough yet durable/thick enough for blitzballs and other “heavier” balls has been difficult. It’s taken over two years to find the right combination of materials. This beauty is made of Carbon Fiber, Synthex and Spectra. K12 is in reference to the thickness of carbon used. It’s twice as thick as the carbon used in our wiffleball bats. This and the use of our new synthex material was the key to success. We’ve developed a bat that swings great, has great pop and is durable. We offer the same one year warranty on this bat as our wiffleball bats. Enjoy!