The BIO-Light was created for optimum light refraction when used with the BIO-Speculum. It is the brightest and least obtrusive light source available. The Krypton bulb provides unsurpassed shielded light due to its unique recessed design. No more glaring light in your eyes! The BIO-Optic Retainer (included with the BIO-Speculum (BS-200) holds the light firmly in place. Two AA batteries included.