If you are making your own eyepieces, this lens is for you. Combine this with other elements to make Modified Plossl, Erfle, Reverse Kellner, or other designs. This is the hard to find special doublet that will help make your eyepiece designs spectacular. Cemented doublet with steep curves. Not achromatic by itself. 33mm diameter by 360mm focal length. Old Edmund Scientific stock designed for some of their eyepieces. Get creative with this. Unused.