| Business | Phone |
| A & R Engineering 7322 Westmore Rd, Rockville 20850 | (301) 315-0597 |
| Able Engineering 421 N Stonestreet Ave, Rockville 20850 | (301) 279-0418 |
| Summertime Inc 315 Howard Ave # B, Rockville 20850 | (301) 309-0119 |
| Service Machine Shop Inc 12336 Wilkins Ave, Rockville 20852 | (301) 881-5934 |
| Precision Engineering Co 315 Howard Ave # A, Rockville 20850 | (301) 251-9650 |
| Fjb Engineering Co 330 N Stonestreet Ave # I, Rockville 20850 | (301) 424-2509 |
| Halpro Inc 155 Woodland Rd, Rockville 20850 | (301) 762-1223 |