| Business | Phone |
| Advanced Detection Tech 19131 Redwood Rd # F, Castro Valley 94546 | (510) 886-1620 |
| Alertex Security Systems 5860 Charter Oaks Dr, Castro Valley 94552 | (510) 886-8866 |
| Kestone Security Systems Po Box 2527, Castro Valley 94546 | (510) 420-1730 |