Purex Fels-Naptha 5 oz. Heavy Duty Laundry Bar Soap is a powerful stain remover that has been trusted for over 100 years. It is ideal for pre-treating greasy, oily stains like perspiration and ring around the collar. To use, simply rub the stain with a wet bar of Purex Fels-Naptha and let it sit for a few minutes before washing your clothes as usual.