This children's baseball uniform was worn by Ken Koster (at age 9) of Grand Rapids, Michigan around 1949 and was created by Harvard Sportswear. The grey wool jersey features red piping along the sleeves, neck, and placket. 

This uniform was collected along with the uniform of his grandfather's Gerrit Koster who played semi-professional baseball in Grand Rapids between 1900 and 1905. He often pitched for the Charles Thomas baseball team. A news story in the Grand Rapids Press, Monday April 18, 1949 was featured with Koster and his grandsons Ken Koster and Dickie Roeters in baseball uniforms (two which are now in GRPMs Collection). This uniform was donated by Gerrit Koster's granddaughter-in-law, Megan Willems-Koster.