GE Silicone I Window & Door – permanently weatherproof - GE Silicone I* Window & Door caulk can withstand all weather conditions and will remain permanently waterproof, flexible and shrink-/crack-proof. Outdoor elements such as heat, sun (UV rays) and extreme cold can cause acrylic to crack and crumble over time, leaving gaps for air and water to seep through. Those leaks can lead to water damage, mold growth and higher energy bills. Why 100 percent silicone? Unlike acrylic, silicone is permanently: Waterproof—Acrylic breaks down in water over time. Flexible—Acrylic becomes less flexible and can even freeze at low temperatures, making it more likely to crack. Shrink-proof—Acrylic shrinks as the caulk dries. This shrinking can cause cracks over time. Crack-proof—Acrylic hardens, cracks and crumbles over time when exposed to extreme heat and the sun's UV rays. Made in USA.