Assertion: eyepiece's inch | /r/HasProperty | 31.5 mm
Facets:
Source sentences:
text: The barrels of all modern astronomical eyepieces manufactured in the United States have either a 1.25 inch (31.5 mm) or 2 inch (50.5 mm) nominal exterior diameter; many older eyepieces some eyepieces manufactured in Japan have a 0.965 inch (24.5 mm) nominal diameter.