Assertion: nagler eyepiece | /r/AtLocation | its original form
Facets:
Source sentences:
text: The Nagler eyepiece, a patented design whose name is also a trademark, available from TeleVue, is shown here in its original form (current Nagler eyepieces use more exotic glasses, have a more advanced design, and are, as a result, somewhat more compact for any given focal length):