Whinkwhink Rust Stain Remover, 16 Fluid Ounce

Absolutely brilliant stuff. I had a couple of Karate Gi's riddled with brown stains after a bunch of keys were left to rust in the washing machine. Soaked the gi's and applied a couple of drops of stain remover. You could actually see the stains disappear before your very eyes. This worked where other oxy powders, stain bars, etc. failed. Can't recommend it highly enough (just use with caution).