Fabri-Kal's RK Cup Lids fit easily and securely onto compatible 16 oz and 20 oz RK Cups (sold separately). Made from high impact polystyrene, a versatile, durable plastic. Includes straw slot for enjoying beverages on the go. Designed with flavor buttons to identify beverage selection. Fits: 16 oz to 20 oz Cold Cups; Material Type: Plastic; Material(s): Polystyrene; Color(s): Translucent.