For 2 1/2" and 3 1/2" (65 and 90mm) or deeper hollow walls with finished wall surfaces 1/4" to 1 1/2" (6 to 38mm) thick. Corrosion resistant stainless steel. One required for each flange. Fastener will support 300 lbs (136 kg) load. WingItTM is a trademark of WingIt innovations, LLC.