Dedicated eyepiece with variable magnification for use with specific EDG series Fieldscopes. Delivers bright, clear images at 20-60x magnification when attached to an EDG Fieldscope model with an 85 mm objective lens, and at 16-48x magnification when attached to a model with a 65 mm objective lens. Features a bayonet-type mount with lock for quick and secure attachment to the Fieldscope. With a long eye-relief this zoom eyepiece is a great choice for viewing subjects from variable distances, even if you wear glasses.