First class and Finer

First class noun - Mail that includes letters and postcards and packages sealed against inspection.

Finer and first class are semantically related. in better topic. In some cases you can use "Finer" instead an adjective phrase "First class".

Finer adjective - (comparative of `fine') greater in quality or excellence.

First class and finer are semantically related. Sometimes you can use "First class" instead an adjective "Finer".