Meade Instruments 07174-02 20mm Super Plossl Series 4000 Pinpoint Edge-of-Field Sharpness (52 Degrees) Long Eye Relief Extremely Low Astigmatism, Spherical Aberration, &amp; Off-Axis Color 7-Layer Multi-Coating &amp; Edge-Blackened Optics Soft Rubber Eye Guard with Bayonet Mount (Included)