The International Crystal Manufacturing Company is a family-owned, business established in 1951 to provide crystals, oscillators and filters for the military. Since its inception, it has expanded into the United States manufacture of quartz crystals, oscillators, filters, and TCXOs / VCTCXOs used in military applications, communications, microwave transmission, data acquisition and transmission, and cutting edge research. Crystal Manufacturing has purchased Sentry Manufacturing to help it better serve its customers by expanding product lines, production capabilities, technical abilities and market presence. The International Crystal Manufacturing Company has offices in Oklahoma City.