Wikipedia
The Rampuri is an Indian gravity knife of formidable reputation having a single-edged blade roughly 9 to 12 inches long. Usually it is the switchblade type but there are step-lock types available as well. It formed the basic weapon for Indian thugs or " goondas" during the beginning of the 19th century. The name Rampuri comes from the town of Rampur, Uttar Pradesh. The royal bladesmiths of local Nawabs of Rampur started making knives after the popularization of firearms after the 18th century.
The Rampuri is still in use today as a crime weapon, by the local Indian Mafia although locally made guns and sophisticated automatic pistols have largely taken their place. However, in mid 1990s, the Government of Uttar Pradesh banned making such knives longer than 4.5 inches of blade length, which led to the drop in popularity of the knife, which even made its way to crime thrillers of Bollywood in the 1960s and 1970s.