Double Bubble clocks, made from the 1940's to the 1960's are well known for being the most attractive of all the advertising clocks, and each of these clocks are beautiful.  The clocks get their nickname, 'Double Bubble'  because there is an inner crystal or glass bubble which displays the company logo. The hands of the clock are sandwiched between an outer crystal or glass bubble which usually displays the numbers of the clock.   Limited production on many clock models is the rule, rather than the exception. look for the clocks to become as collectible as the originals once we've sold out the run.