Koch Industries 4021521 PTO Locking Pin with Square Wire Retainer, 1/4 x 2-1/2-Inch, Yellow Zinc Plated, 2-Piece Square wire retainer Diameter 1/4-Inch Useable length 2-1/2-Inch Used in farm, lawn and garden, trailer hitch receivers, and other applications to secure attachments and PTO accessories Pins comes in poly bag