Koch Industries 4045213 PTO Spline Adapter with 1-3/8 by 6-Inch Male Spline and 1-3/8 by 21-Inch Female Spline Connect implements to a tractor's PTO shaft Allows for power to be transferred from the tractor to the implement Male Spline 1-3/8 by 6 and Female Spline 1-3/8 by 21 Adapter 21-6 Yellow zinc plated finish