Manufacturer's part #01 LAO 639. Original price: $85.00. Made of crown and flint glasses (not cemented, but we sell balsam), design wavelengths are 486.1nm, 589nm, and 656.3nm. 30mm diameter with a focal length of 300mm making this an f/10. Edge thickness is 8.5mm, center thickness is 9.4mm. Edges have a .25 - .50mm bevel. Unused.