This Is An Add On If You Have Already Purchased A 3 Piece System Patented Base Crossmember Universal Wood Holder Can Use A 4x4, 2x4 Skinny, or 2x4 Fat Depending On Bolt Setup Heavy Duty Crossmember - Should Last Forever Base Materials - 1/4 inch Mild Steel Flats and 3/16 inch Laser Cut Dimensional Steel Standard Fastener - 1/2 inch Bolts Using A 3/4 inch Socket No Stakes 16 Pounds Total Comes Treated with a Rust Inhibitior, Ready For Paint