The difference between the Spatz of Egg 12 and the one in Egg 20 is one year as the last one is from 1955 and the first is from 1954. Also the prospect refers to an Export version that includes a different windscreen with a full metal trim, screen wiper and side spot lights. Curiously such prospect doesn't mentions the name Spatz, instead says " dreirad-dreisitzer" (3 wheels-3 seats)