These standard lids are the only beverage lids that use magnets to lock your water, beer or favorite drinks. The cover adds a protective barrier to keep the beverage sealed and prevent heat or cold from escaping. Please note that the cover is not leak-proof and not prevent overflow. Twenty ounces. Made of stainless steel, double-layer vacuum insulation protects your hot or cold drinks at all costs. 20-ounce flat-bottomed cup, the size of the glass fits the standard-sized cup holder.