| Business | Phone |
| Heitz Engineering Roseville 95661 | (916) 773-8290 |
| Monolithic Engineering Inc 407 Lyndhurst Ave, Roseville 95678 | (916) 786-8024 |
| Oak Engineering & Development 609 Oak St, Roseville 95678 | (916) 782-2039 |
| Enercal Engineering Inc 1212 Coloma Way, Roseville 95661 | (559) 432-2236 |