more eyepieces

At my request, Mom brought down her 2 extra eyepieces from her telescope. They're Meade eyepieces, marked as 18mm and 4mm. She also brought the unidentified Edmund.



They're 1¼" in diameter. That means all her eyepieces are compatible with my telescope and visa versa. And with my doubler, we now have 8 total eyepieces ranges each (although the 4mm Meade is useless in mine)! Awesome!

I don't know the type or design. The "OR" printed beside the focal length suggests they're orthoscopic. Scoured the net but I couldn't find any information about them.

I'd like to know their apparent field of view but I'll have to calculate it backwards, measuring the true view...