The tough bulls from Monkey Business rush into your shoes and are designed to refresh your footwear at the end of they day. They are practical and can also be used to purify the air in closets, wardrobes, gym bags or stuffy lockers. The Sneaker Peekers set includes four bags of eco friendly activated charcoal, which can absorb smells effectively for up to 6 months. Place a bag in each bull and keep the remaining bags as replacements.