We have produced these large flange bolts after our customers loved there front wing bolts with the same built in flange.
With the increased surface area it decreases the chance of the floor buckling where just your regular bolt and washer come through which loosens them and then ultimately falls out.
Kit consists of
10x 1/4 unf 1/2" long
4x 1/4 unf 3/4" long
14x 1/4 unf jet nuts