Penny applies an algorithm based on real-time data to ensure the best BIN is selected when you generate a card, this ensures the best acceptance and the highest possible interchange return.
The card_bin parameter can be provided when issuing a card to choose a particular BIN instead of using the dynamic allocation algorithm. The list of active BINs can be found via the list BINs endpoint. You can use this to find a BIN that is suitable if it is being blocked by a merchant.