A .38 Police Special or simply .38 Special is a solid projectile weapon made specially for police and law enforcement officers on Earth issued in the 20th century. Despite its name, the caliber of the weapon is 0.357 inches.
Lieutenant Sulu professed to be an avid historic gun collector. While on shore leave on the Omicron Delta Shore Leave Planet, Sulu found a .38 Special lying on the ground, after which he decided to have some fun by discharging the weapon, alerting the attention of Captain Kirk and Spock. Kirk later on used it to "kill" the Black Knight when phasers weren't working. (TOS: "Shore Leave")