Mark's Auto Lockout Services
| Oasis | Trailer/RV | O1122 |
| Odeon | dune buggy | 1120D |
| Olympic | 1171, 1171B | |
| Olympic | RV | 1307A, 1146 |
| Olympus | padlock | 1003A, D4292, SC1 |
| On Guard | O1122A, K1122D, 997E | |
| Otasco | freezer | O1122 |
| Overhead | garage door | 999, 1004, 1141GE, X1014L |