How do you make sure the Health Monitor has enough straws? It means you need staff to check and refill the straws every few days if the straws are stored within the machine. Multiple times a day if they are in a dispenser, because kids will take them all. Have you taken into account the costs of refilling straws?
This has been considered and that's why after payment, the customer must take a personal straw provided by the individual and insert it into the corresponding hole of the health monitor .