California Code, Business and Professions Code - BPC § 12210

(a) Each sealer shall, within his or her county inspect, try and test all weights, scales, beams, measures of any kind, instruments or mechanical devices for weighing or measurements, and tools, appliances and accessories connected with any or all such instruments or measures, sold, or used by any proprietor, agent, lessee or employee for commercial purposes, as defined in subdivision (e) of Section 12500.

(b) Each sealer shall, when so directed by the board of supervisors of his or her county, and only upon the written request of any person, firm or corporation, calibrate, test, weigh, and measure, and certify to the accuracy of, noncommercial weights and measures and weighing and measuring devices, and instruments, tools, and accessories connected therewith. The board of supervisors may authorize the sealer to establish from time to time a schedule of fees to cover the cost of such service and to charge and collect the fees.