A manufacturer of high-end leather bracelets uses a kanban system to control material flow. The bracelets are transported in sets of 12. A cutting operation, on average, produces approximately 200 bracelets per hour. It takes one hour for the sets of collars to be replenished. Due to variations in processing times due to the size and length of the bracelets, it has been decided to keep 25 percent of the needed inventory as safety stock. How many kanban card sets are needed?