Radar Gun (1975)

Described extensively in article about its use by former Major League pitcher Danny Litwhiler, head baseball coach at Michigan State University, who is widely credited with the first use of a radar gun to detect pitch speed. “Litwhiler Uses Radar to Record Mound Speed.” Bob Gross, Lansing State Journal, March 8, 1975, pC-4

No earliest use given in 2009 Dickson Baseball Dictionary