Pinhole Resource Micro Drilled Pinhole Set of 12 in individual 1.5" square sheets of .001 full hard stainless steel. Holes measure .0059", .0087", .0102", .0126", .0138", .0160", .0181", .0200", .0225", .0250", .0276", .0320". Optimal fit for 3/4" to 17" focal length includes an optimal pinhole size, length, and exposure chart.