Ever suffer from some armpit sweat when wearing white shirts and notice yellow stains from the deodorant on the shirts after wearing the white shirts after a period of time? This can be upsetting because we like the white shirts or spent a good amount of money on the white shirts only to have to get rid of it shortly. I think a great solution to fixing this problem with stains in armpit area of white shirt sleeves would be creating a cloth that could be worn in the armpit region while wearing the white shirt that prevents that from happening so the problem can be solved. Its easier to wear a tee shirt under a polo but for tee shirts, if they could come up with a cloth just for the armpits it would be a great invention. I wonder why this hasn't been invented yet?