The EasySeal line has proven to be the number one trusted leak sealant brand for years, with millions of leaks sealed. Now Nu-Calgon has made EasySeal even better with EASYSEAL ULTIMATE the strongest and fastest leak sealant on the market, now with the ability to treat systems up to 10 tons in one application! Permanently seals even larger leaks Rapid Fusion Technology for a stronger bond Easiest to install direct inject Works with all refrigerants Treats larger systems New brighter UV dye on 4050-11, 4050-12 and 4050-21