Manufacturer's part # 01 LAO 139. Original price: $76.00. These are not cemented (crown and flint) and uncoated. Surface accuracy is .25 wave at 546.1nm, design wavelengths are: 488nm, 546.1nm, 643.8nm. Clear aperture 27mm, center thickness is 9mm, edge thickness is 7.1mm, surface quality is 60-40 scratch and dig, centration is 3 arc minutes. Unused.