| Business | Phone |
| Baker Engineering Inc 1520 Merritt Dr, El Cajon 92020 | (619) 579-9333 |
| Kenneth H Barrett 207 S Sunshine Ave, El Cajon 92020 | (619) 442-5864 |
| Baseline Engineering 205 Claydelle Ave # 105, El Cajon 92020 | (619) 442-0494 |
| Hatra 1010 Singing Ridge Rd, El Cajon 92019 | (619) 440-6533 |