5/16" x 1.5" Lag Bolts w/ Flat Washers - For Use with Big Blue Brackets and Housings Four lag bolts and flat washers used to attach Big Blue filter housings to the bracket Bolts measurs 5/16" x 1.5" Flat washers measure 5/16" Includes enough bolts and washers to attach one housing, so you will need one set per housing