 The over-frock, like other body coats, could not survive the increasing cost of the bespoke tailoring required to make them fit properly around the waist to create the classical "hour-glass" silhouette.In the first decades of the 20th century, it was replaced by sack overcoats like the Chesterfield coat, the guard's coat, and the Ulster coat and the Inverness coats and such, mirroring the change from frock coats to modern suit jackets.The expensive over-frock became impractical in comparison.