Pennwood Unfinished Red Oak Solid Hardwood 11/32 in thick x 7.5 in wide x 48 in Length Riser, $21.99 USD/Box, LL Flooring (Lumber Liquidators)

Designed to fit on the face of a stair riser, it complements the lower stair tread or hardwood floor. Comes unfinished, allowing customization to match your decor.