What is Coinbase card & how does it work?

Could you elaborate on the Coinbase card and its operational mechanisms? Specifically, I'm curious to understand how it integrates with cryptocurrency and traditional finance. Is it a physical card or a digital one? How does one acquire it? What are the key benefits and drawbacks of using it? Does it allow for instant conversions of crypto to fiat currency for purchases? Additionally, what are the security measures implemented to protect users' funds? Lastly, how widely is it accepted for payments, and what are the fees associated with its usage? I'd appreciate a comprehensive yet concise overview of the Coinbase card.