Professional Grade Acidic Formula: versatile, multi-surface usage; use on tile, grout, metal & concrete; for plumbing fixtures, appliances & counters. Trusted pro quality since 1937. Pros know that acids are required to remove calcium, lime scale and rust. This professional grade concentrated acidic solution breaks up deposits quickly, removing stains & buildup that other cleaners cant. One-year limited warranty. www.zep.com Questions? 1-888-805-Help. Also try Zep Mold Stain & Mildew Stain Remover, a powerful pro-grade bleach cleaner. Made in USA.