This plate is made in low carbon steel in dimensions 5 3/8" x 5 3/8" x 1/8". The plate has two 5/16" holes, two 1/4 " slotted holes, four 3/8" oval holes, and four raised lugs to fit outside dimension of the column. One 9/16" counter sink hole is center located to attach the column. One 1/2 " hex head screw is included in the packaging