Mark's Auto Lockout Services
| U.S. Lock | 1179, 1145 | |
| U-Haul | padlocks | OKB54 to OKB57 |
| Unican | 1041T | |
| Union | (Wilmot Breeden Union) | Various British cars |
| Union West | padlocks | 1092NTG |
| Uniprise | padlocks | Master, Viro, MDK |
| Unit padlock | X1014F |