The importance of choosing a quality eyepiece cannot be overstated. In many ways it is the most important factor in determining overall spotting scope performance. Fortunately Pentax makes some of the finest in the optics industry. The Pentax model #70509 is about as good as it gets when it comes to eyepieces.
The #70509 was specifically designed to maximize performance from the 80mm and 100mm model Pentax Spotting Scopes.
Magnification Range & Eye Relief:
Pentax Spotting Scope 80mm to 100mm: 20x to 60x
Eye Relief: 11 to 15mm