Check the listing for details. RAM Track Ball 1.5" Ball Mount with Rectangular Plate for Humminbird Helix 7. Condition: New, Made in USA. Listed at 66.99 USD. Features: ---RAM Track Ball with 1.5" rubber ball molded to a high strength composite base with rubber friction washer and a stainless steel T-bolt ---T-bolt is designed for easy installation, adjustment and removal from virtually any track system ---Simply insert or slide the Track Ball into your track and twist the ball clockwise to tighten in place - Twist counterclockwise to loosen or adjust the ball ---T-Bolt Dimensions: .48" x .95" - Fits a variety of tracks ---Standard length double socket arm - Overall arm length: 5.625" ---A single spring inside the arm opens the end sockets, allowing you to pivot the ball and socket connection ---2" x 4" plate with a four hole pattern and 1.5" rubber ball ---Plate thickness: 1/4" - center to center hole pattern is 1.5" x 3.