Designed to hold the boresight model WK-29-9135 and provide a method to align a long platform or any surface which requires a precise alignment of preset points at increments along its entire length. Shown above with the WK-29-9135S Mark 75 Boresight Telescope. The MARK 75 is generally held by a bracket or v blocks. This telescope screws onto an sights through cross wires fitted into the fixture openings. Magnification: 8x. True Field: 3°-30′. Exit Pupil: 2.5 mm. Eye Distance: 18 mm.