| Company | Group | Feature | Description |
|---|---|---|---|
| Westclox | Big Ben Style 1a | Back | Style 1a Big Ben clocks have a series of patent sequences on the back. The patents were in two different locations. Later backs have patent numbers instead of dates. |
| Westclox | Waralarm - Fiber Case | Back | Early examples have a price label, later ones have the price imprinted in the back. |
| Westclox | Model 66 Movement | Alarm Set Knob Fastening | Early 66 movements have screw on knobs, later they are staked. |
