A problem sometimes encountered in using a high power magnifier is the lack of sufficient light on the object. A bulb inserted in the groove of the Coddington lens illuminates the object being examined eliminating this problem. Requires two AA batteries (not included). - Correction in the coddington magnifiers is achieved through the use of a single thick lens with a central groove diaphragm. This provides for sharp, crisp images. A little trivia "Coddington" Magnifiers got their name from their British inventor, henry coddington.