With the advent of the bottle cap, beer producers took the opportunity of advertise their products on the bottle cap opener.  Lemp was no exception.

 

According to the "Just For Openers" web site, many older bottle openers have a small square hole called a "Prest-O-Lite Key".   It was used to turn the valve on automobile gas headlights from about 1910 through the early 1930's before electric headlights were widely used.

 

The following are examples of openers produced for Lemp products.