Exponent biomechanical and electrical engineers have also analyzed less-lethal electronic restraint devices employed by law enforcement personnel. These devices typically operate at high voltages, high frequencies, and low currents to stimulate and immobilize the musculoskeletal system. Exponent has refined the method of accurately determining the output power delivered to a load, has measured the accuracy of darts fired using devices made by different manufacturers, and has evaluated whether muscular contractions elicited by the electrical stimuli would be harmful.