Mycelium, a bitcoin wallet company, has announced the long-awaited release of its bitcoin card. The card allows users to complete transactions without an internet connection and with lower fees than traditional payment systems. Unlike debit cards, Mycelium cards can only be used with merchants that accept bitcoin. However, Mycelium believes its model keeps infrastructure simple and costs low by relying on blockchain technology rather than a traditional payment processing network. Critics argue the cards are still limited in usage and that regulation poses challenges to widespread adoption.