 Kaiser wore uniform number 21 when the AL adopted numbers for umpires in 1980.Kaiser officiated in the World Series in 1987 and 1997, as well as the All-Star Game in 1991.He also umpired in the American League Championship Series in 1980, 1988, 1993 and 1995 (Game 6), and in the American League Division Series in 1981, 1996 and 1997.