RAW 500's are creaseless for smoother burning. Perfectly made from naturally unbleached plant fibers, and finished with the purest natural gumline for a consistent steady burn. Designed to satisfy even the most discriminating smoker. With the truly natural gum with NO preservatives, a slight curl may appear at the gumline in low humidity naturally. If they curl just hold the sheet tight and blow warm air, just exhale onto the gumline. That will straighten them right out!