THIS DESIGN IS A 3/8"STEEL PLATE/SLOTTED BOLT MONTING PATTERN FOR ADJUSTABILITY / all edges are radius smooth.THIS PART INDURES THE CONSTANT IMPACTS FROM THE PINS/THE TOP PROTECTOR SLEEVE PROVIDES A SAFE NON SCUFFING LANDING PAD FOR THE BOWLING BALLS THAT GET DERAILED FROM THE BALL WHEEL ELEVATOR DURING VERTICAL LIFT TO RETURN TRACK.THERE ARE MANY REASONS WHY A BALL CAN GET DERAILED! THIS PART PROVIDES A NO [CONTACT] BETWEEN BALL /BALL ELEVATOR EDGE!!! ALSO GIVES THE MECHANICS TIME TO REPAIR/MAINTAIN THE BALL RETURN ASSY! INSTEAD OF REPLACING THE CUSTOMERS BALL!!!