The Smith Corona Company started in Gun manufacturing then in the 1930's after the depression they launched a line of new portables: Standard, Sterling and Silent all with a flat top style.
This was the first sterling was introduced in the flat top design and silver rimmed keys. To launch their new series they actually produced a small amount of bodies in sterling silver for window displays!
In 1939, this style was replaced by the "Speed line" design. The Speedlines continued through 1949, after which they were superceded by the Super-5 body.
The Sterling continued to be produced with different body styles and functionality until the 1970’s.
The Sterling photographed above is one of my favorites you often see me list and do custom! The 5AX Sterling model is a popular model because it features SCM's most modern and solid mechanism surrounded by SCM's more-streamlined body style of the past.