A wallet band is an elastic band used to secure cards or cash for those who do not wish to carry a bulky wallet

Wallet

A wallet, or billfold, is a small, flat case that is used to carry personal items such as cash, credit cards, identification documents , photographs, business cards and other paper or laminated cards...

 or money clip

Money clip

A money clip is a device typically used to store cash and credit cards in a very compact fashion for those who do not wish to carry a wallet.-Metal :...

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Rubber band wallet

The rubber band wallet is exactly what the description says: a rubber band used to secure cards or cash. Several companies have commercialized the rubber band wallet by adding ornamentation or changing the dimension of a traditional rubber band to work more effectively with credit cards and currency. The rubber band wallet has limited durability and is prone to collect grime, which has given rise to alternatives.

Elastic wallet band

The elastic wallet band is a variation of the rubber band wallet. An elastic wallet band utilizes fabric, rather than straight rubber, to secure the cards or currency. Several variations of this product exist; some integrate rubber on the inside to achieve the gripping properties of a traditional rubber band and others utilize multiple fabric bands to separate currency from cards.

Swallet

The swallet is a combination rubber band and neoprene

Neoprene

Neoprene or polychloroprene is a family of synthetic rubbers that are produced by polymerization of chloroprene. Neoprene in general has good chemical stability, and maintains flexibility over a wide temperature range...

pouch used to secure a few cards and currency.