We love using these fiberglass patches as a preventative measure on the keels of our hard-shell kayaks to protect them from rocks and other hazards both in and out of the water. RapidFix UV Fiber Patches are UV or sunlight activated. They come out of the package pliant and flexible, self-adhere to your equipment, and then harden when they cure with light. The patch is made out of fiberglass reinforced polyester that creates permanent bonds for repairs that last. They are non-flammable and non-toxic. Patch Size: 6" x 6"