JW,
It's made by a company called "Mean Green" and the product is called  "Mildew 
Stain Destroyer". I buy it at the local Dollar General store. It's  usually 
in back by the cleaning supplies.
This stuff works great if you spray it on, leave it alone and come back in  
fifteen minutes or so and rinse it off. I just noticed the label, it says $2.00 
 a bottle....I was previously in error, but it's still a bargain.
 
Rummy