DESC: Features:Halogen HPX lamp provides 30% brighter, whiter light output for true tissue color and consistent, long-lasting illumination.Coaxial optics produce a shadow-free spot, easier entry into undilated pupils, and a larger field of view.Polarizing filter virtually eliminates corneal reflection.Red-free filter may be used with any aperture.Sealed optics keep out dust and dirt for years of maintenance-free operation.Product Information:Additional Features include: 18 unique aperture/filter combinations for greater versatility: micro, small, and large spot sizes, cobalt blue filter for corneal exams, fixation target, and slit aperture (all on a 6-position, continuously rotating aperture dial). Plus: red-free filter, polarizing filter, and unfiltered Halogen HPX on a 3-position switch--each position can be engaged with each of the 6 positions of the aperture dial, for a total of 18 possible combinations. Rubber brow rest prevents scratching of eyeglasses. 28 focusing lenses with a range