Pullovers are a type of clothing that can be worn for both casual and formal occasions. They come in a variety of styles, including polos, slipons, and sweaters. Polos are short-sleeved shirts with a collar and buttons down the front. Slipons are pullovers with no buttons or zippers, usually made of lightweight fabrics. Sweaters are heavier pullovers, often made of wool or cotton, and typically have long sleeves.