A hand-held surgical instrument intended to be used to establish a horizontal line or plane relative to the site of interest by means of an air bubble enclosed in a slightly-curved glass tube. When the bubble is aligned within the established settings (e.g., a centre circle, two lines) the horizontal has been established. The device is utilized to ensure that an orthopaedic device and/or instrument is in the centre of a specific plane (i.e., lateral, cephalad, caudal). The device may include a mechanism to mark the established centre point. This is a reusable device.