The listing is for 8pcs White POM Ferrule(Shaft) Collets, they work for 8 sizes as below, 12.00mm, 12.25mm, 12.50mm, 12.75mm, 13.00mm, 13.25mm, 13.50mm, 13.75mm Kindly Note, Collet ID is 0.007"-0.01" smaller than labeled size, but groove expension provide a just fit to the labeled size.