Angled structural member with recessed thin wall for drilling or knock-out

A structural member extending in a longitudinal direction having a substantially L-shaped cross-sectional contour forming a pair of substantially orthogonally directed leg members, each of said leg members having opposing sides forming an inner surface and an outer surface defining a thickness dimension of said leg members, each of said leg outer surfaces forming a planar contour and each of said inner surfaces having formed therethrough a plurality of blind openings defined by a plurality of first recesses having a first opening recess dimension and a plurality of second recesses aligned with respective ones of said first recesses and having a second opening recess dimension less than said first opening recess dimension, each of said first and second recesses in combination having a thickness dimension less than said thickness dimension of said leg members.