S2O 3-pack Portable Stain Removing Pen Kit Does it seem like stains stalk you wherever you go? Harness a handy stain soldier with the S2O Stain Removing Pen Kit. These three .5 oz. pens contain a fabric-friendly formula that helps remove a variety of stains. Keep them in your purse, briefcase or glove compartment as a convenient solution to your cleaning challenges.