The 157 158 National Interface Board (D9989-838) is a specific model designed for vending machines. This interface board, from the trusted brand National, serves as a crucial component for connecting and controlling various functions of the vending machine. It is compatible with models 157 and 158, providing a reliable and efficient solution for maintaining and operating vending machines in a restaurant or food service setting. This specific model helps ensure seamless functionality and compatibility with your existing vending machine system.