See Downloads Tab above for ASI 1214-1 technical data sheet (.pdf)

Heavy-Duty Shower Curtain Rod Flanges are fabricated of alloy 18-8 stainless steel, type 304, 20 gauge. Flanges are provided with (3) dimpled 13/64" (5.2mm) dia. holes to accept No 10 oval head screws (furnished by others). For 1" O.D. shower curtain rod stainless steel x 18 gauge.