This is a Precision Pocket Ruler, a versatile layout and measurement tool designed primarily for woodworking [1, 5, 7]. Machined from durable anodized aluminum, it features an adjustable slide stop that can be locked anywhere along the blade to ensure repeatable markings or to act as a depth gauge [2, 9]. Its unique design includes a rectangular cut-out that allows the ruler to stand vertically for accurate height checks of saw blades or router bits [4, 7].