Natural products, free of chemical additives and preservatives, change and mature with age.Tobacco is no exception and this is especially true of in two ways.I suspect it was introduced in the 1960's as a substitute for the 'knife lid'.
The removable top of this type of tin is about a quarter inch smaller than the circumference of the tin.
The top is levered open via a lever that is permanently hinged to the top.
It appears that the fixed cutting point style was the first to be used and was phased out in the early 1950's.
I am not certain when the movable cutting point style began use but I have seen it on tins dating to at least the 1930's, and it was the predominate style after World War II and the only style after the early 1950's.
First, preservatives will retard the aging process.
Second, the chemicals and the tobaccos will neither uniformly age nor maintain the original balance of flavors.
The 'coin twist' tin, which is still used today, appears to have been introduced in the 1940's following World War II and by the '70s became the predominant tin style.
Some early 'coin twists' dating to no later then the early 1950's had rubber gaskets that extended past the outer lip of the top or rubber stoppers that plugged a hole in the bottom of the tin.
The inner top is a thin metal sheet which an air seal until the initial opening of the tin.