Spancare 13mm Dia achromat Doublet Lens with 20mm Focal Length for Telescope Eyepiece

Useful for making plossol and kellner eyepieces Achromat doublet 20mm focal length 13mm dia achromat doublet lens with 20mm focal length for telescope eyepiece 20mm focal length Useful for making plossol and kellner eyepieces 13mm diameter Achromat doublet Item Weight : 180 g Product Dimension : ‎13.6 x 13.2 x 10 cm;