V7653, 12 Pack, Zinc Ribbed Neck Bolts & Nuts, 1/4-Inch Diameter x 20 Threads Per Inch x 1/2-Inch Length, HoLight Duty 2 Or More Parts Together, Tighten Without Being On Both Sides Of The Door, Knurled Shank Prevents Bolt From Spinning During Installation & Tightening, C an Be Used To Join Metal Angles & Track Brackets, Primarily Used On FiberGlass Garage Doors, Carded.