Superior Pro-Siliconized Acrylic Whisper Grey Sanded caulk is a premium one-part formula with professional workability, flexural strength and resistance to a broad spectrum of fungal, algal and bacterial growth. Suited for both interior and exterior applications, this long-lasting and flexible caulk is also stain, mold and mildew resistant. Find the perfect shade for your project in our assortment of colors. For full product details, view the product data sheet.