The Alpine Astronomical Baader 12.5mm Micro-Guide Eyepiece with Log-Pot Illuminator is designed for making astronomical measurements during deep-sky observations of deep-sky objects like double stars and clusters. It includes four scales for linear and angular measurements. A Log Pot illuminator screws into the side port of the eyepiece to illuminate the scales in red light while preserving night-adjusted vision. It features a rheostat to adjust the light's intensity for easy and comfortable viewing. The eyepiece fits standard 1.25" focusers and accessories, and its 12.5mm focal length produces a moderately-high magnification on most large aperture and long focal length telescopes.