| Business | Phone |
| 3 D Technical Svc 950 Detroit Ave # 15, Concord 94518 | (925) 691-5543 |
| Controlco 5600 Imhoff Dr # G, Concord 94520 | (925) 602-7728 |
| Seco Control Systems 930 Detroit Ave # F, Concord 94518 | (925) 798-8300 |
| Telstar Instruments Inc 1717 Solano Way # 34, Concord 94520 | (925) 671-2888 |
| Ortman Electronics 936 Detroit Ave # N-M, Concord 94518 | (925) 609-1609 |
| Viking International Inc 5235 Pebble Glen Dr, Concord 94521 | (925) 825-6900 |