This U.S. industry comprises establishments primarily engaged in manufacturing and/or assembling: clocks; watches; timing mechanisms for clockwork operated devices; time clocks; time and date recording devices; and clock and watch parts (except crystals), such as springs, jewels, and modules. Manufacturing glass watch and clock crystals--are classified in Industry 32721, Glass and Glass Product Manufacturing; Manufacturing plastics watch and clock crystals--are classified in U.S. Industry 326199, All Other Plastics Product Manufacturing; and Manufacturing timing relays--are classified in U.S. Industry 335314, Relay and Industrial Control Manufacturing.