The picture below shows a larger front and back view of this Old Oldsmobile & Lark Mansfield Massachusetts Auto Dealer Advertising Premium Key Chain. The keychain is not dated but it is believed to be from the 1950s (1950 -1957). It has a metal bead chain. Encased in clear plastic is a card. One side has a blue and silver embossed emblem or logo with the planet Earth with a ring and stars. It is marked on the two sides as follows:
OLDSMOBILE MANSFIELD MOTORS,INC. OLDSMOBILE - LARK MANDFIELD, MASS. TEL. ED 9-7851 THE ACTION LINE U.S.A.
The key chain fob alone measures 1-1/4'' x 2''. It appears to be in mint unused condition as pictured.