Here’s the simple (and really effective!) answer to the pills and balls that can mar knitted clothing and blankets. Just rub the Sweater Stone gently over any knit surface and watch as pilling quickly vanishes, and it looks like new again. Keep your blankets, sweaters, hats, clothing and even furniture and fleece, looking better longer, which saves money and resources. 100% natural pumice stone lasts up to 10 years. USA.