Cal. Bus. & Prof. Code § 12505

Whenever a sealer examines any weight or measure or weighing, measuring, or counting instrument used for commercial purposes, and finds it to be correct, he or she shall seal or mark the weight, measure, or instrument with an appropriate device approved by the department, placed so as to provide optimum visibility to the customer, showing that the weight, measure, or instrument was inspected and indicating the date of the inspection.