Capsule. A plastic holder for a single coin or small medal that tightly covers both sides often in an airtight capacity. Capsules are made to fit items of specific diameter and thickness (if the item is not a snug fit in will rotate within the holder). The plastic is very transparent and can be pliable (trade name Cointain) or rigid (made of polystyrene). Such enclosed numismatic items are said to be encapsulated (encapsulated items are often housed in cases where the well is made to fit the plastic holder rather than the coin or medal itself.) See mounting, case.