Custom Shop KH2021 Hardener is a professional-grade urethane activator specifically engineered for use with Custom Shop KC2020 Ultra Flow Clear Coat. Designed to deliver consistent, high-performance results, this hardener ensures proper curing, adhesion, and durability in automotive clear coat applications. Formulated for a precise 4:1 mix ratio with KC2020 clearcoat, KH2021 provides reliable activation that helps produce a deep, high-gloss, wet-look finish. It promotes strong crosslinking within the urethane system, resulting in a tough, long-lasting surface that resists weathering, UV exposure, chemicals, and everyday wear. KH2021 is available in two convenient sizes to match your project needs. The Quart size pairs perfectly with KC2020 Gallon clearcoat, while the Half Pint (8 fl oz) is designed to mix seamlessly with KC2020 Quart sizes. This size alignment ensures accurate mixing, reduces waste, and simplifies the refinishing process for both professionals and serious DIY painters. When used as part of the complete Custom Shop system, KH2021 enhances the overall performance of KC2020 by supporting smooth flow, even leveling, and excellent spray characteristics. The result is a clear coat finish that is easy to sand and buff, allowing you to achieve a flawless, show-quality final appearance. Ideal for custom paint jobs, restorations, and high-end automotive refinishing, Custom Shop KH2021 Hardener is a critical component for achieving professional results. Whether you're working in a shop or a home garage, trust Custom Shop to deliver the quality and consistency needed to get the job done right.