Lanco® Siliconizer Crack Filler™ is a 100% elastomeric styrene/acrylic and modified silicone putty, white and smooth for application with a spatula, suitable for both interior and exterior use. It is formulated to seal leaks and fill cracks of any size. This highly flexible putty adheres to any surface, can be sanded, and will not peel, flake, or crack under adverse weather conditions.