How old is a royal depth control mah jongg set?

A Royal Depth Control Mahjong set is typically considered vintage if it was produced in the mid-20th century, particularly around the 1950s to 1970s. However, the exact age can vary depending on the specific model and manufacturer. To determine its age, you would need to examine any markings or labels on the set, as well as research the production history of that particular style. If it's from the early 20th century or earlier, it could be classified as an antique.