The majority of enlarger focusing aids require that they be placed directly under the enlarging lens because the small mirrors cause the image to vignette as soon as you begin to move it away from the center of the image. The larger rectangular mirror of the Peak Model III Enlarging Focuser allows you to move up to 10° off axis, ensuring that you're able to focus on a critical area. It's aerial image focusing provides a brighter and clearer image than focusers that use ground glass. And it has a "front surface" mirror to prevent ghost images. The rubber rimmed eyepiece includes a focusing ring for diopter adjustment. A superior focuser at an affordable price. Supplied with eyepiece cap, mirror cover, and instructions.