"This 1.25"" Plossl design has a built-in cordless illuminator for use with any make or model telescope and/or off-axis guider. The cordless illuminator has an on/off switch with an integral brightness level control. It uses two 1.5 volt LR-44 button-type alkaline camera batteries or their equivalent (MR-44, SR-44, 357, etc.) Batteries are included with the eyepiece, but are not guaranteed to be charged when received, as the batteries are supplied by an outside vendor and are not covered by the Meade factory warranty. It may be necessary to purchase batteries prior to use. The eyepiece has a dual crosshair reticle with a pair of concentric bulls-eye circles centered on the crosshairs. There are two micro-adjustment controls in the side of the eyepiece. Turning these moves the crosshairs and their circular field stop up/down and right/left within the larger off-axis guider or photoguide telescopes field. This allows you to more easily center the crosshairs on a guide star without having to move the telescope and disturb the photographic composition. The movable reticle does not have central detents or index marks, so returning the crosshairs precisely to the center of the field can only be done by guesswork and is usually not very accurate. If precise centering of the crosshairs in the field is important (for centering stars using the high precision pointing sub-routine in the Meade LX200 scopes, for example), you might want to co nsider going to"