Our 16MM Shoulder Bolt Kit w/Spacers is the preferred method of attaching accessories to your CertiFlat Table. Includes two high strength, 16MM shoulder bolts that are 20MM long, two 12MM Hex Nuts, two 1/2" Washers, and a pair of thick, 5/8" spacers for clamping adjustments. We buy these in vast quantities so we can sell them cheap. This is the same hardware we supply with our fabWings!