SnapNrack Clear Rail Splice Kit, 12 count. At every junction of two rails, snap or slide in a rail splice insert and attach a rail splice top using the provided 5/16-inch bolts and lock washers. On combined single row rail length longer than 35 feet a thermal expansion joint is required. A gap in the rails of 1/4 inch is recommended. Check all bolt torques to ensure that all 5/16-inch hardware is tightened to 12 ft-lbs.