TremPro® 644 RTV is a one-part, general purpose, acetoxy silicone sealant. Basic Uses; TremPro 644 RTV is specially designed for sealant joints between most non porous materials such as glass, aluminum, metal and metal alloys. Industrial and residential uses include HVAC, plumbing and kitchen/bath fixtures. TremPro 644 RTV may also be used on site where a gun-grade sealant is required. Features and Benefits: Easily gunnable over a wide range of temperatures and has excellent adhesion to most common substrates without the use of a primer. TremPro 644 RTV skins within 30 min at 75 °F (24 °C) and 50% RH, and cures into a tough, durable, weather resistant material. It has excellent handling characteristics and tools to a smooth, attractive finish.