| Westclox | Baby Ben Style 4 | Back Material | Most Ivory Style 4 Baby Bens have a steel back which is copper plated then brass plated. A few late ones have a back which is nickel plated then lacquered pale gold. |
| Westclox | Baby Ben Style 5 | Back Material | Most Baby Ben style 5 clocks have a steel back. A few have brass or aluminum back. |
| Westclox | Baby Ben Style 1 | Back | Baby Ben style 1 backs have various patent dates or patent numbers. Early examples have a "Made By" line behind the rear leg. Some examples ca. 1913 have a $2.50 price seal. |
| Westclox | Baby Ben Style 3 | Back | The first ones don't have a Loud-Soft control on the back. The Loud-Soft control was added in December 1932 |
| Westclox | Baby Ben Style 5 | Back | Various U.S. and international patent numbers were stamped on the backs. |
| Westclox | Baby Ben Style 6 | Back | Early backs have PAT. PDG, later ones don't. |
| Westclox | Big Ben Style 1 | Back | Big Ben Style 1 clocks used different patent dates and arrangements on the back. Also, the $2.50 price seal, and various Westclox logos were used. |
| 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. |
