This eyepiece is interchangeable with a standard eyepiece of a boresight telescope. It has a black wrinkle cast exterior. The eyepiece is 1 inch in diameter. The eyepiece can be converted in the field as required to form a straight through vision system or a right-angle system. This eyepiece maintains an erect image and can be rotated through 360° for sighting from any angle perpendicular to the line of sight. Can be adapted to work with Warren-Knight analog or digital video eyepiece system.