Pentax SMC XW 10mm Wide Angle Eyepiece (1.25") - 39x w/ 65mm, 50x w/ 80mm, & 63x w/ 100mm Pentax Scopes Williams Sound EAR010 as those models have a

as those models have a built-in

The Ethos 21mm is a logical choice for owners of the 8mm and 13mm eyepieces

Up to 30-40 dB of Wind Noise Reduction

rubber mount

each capable of taking a 50W load

Pentax SMC XW 10mm Wide Angle Eyepiece (1.25") - 39x w/ 65mm, 50x w/ 80mm, & 63x w/ 100mm Pentax Scopes Williams Sound EAR010 as those models have a70 Apparent Field of View 20mm Eye Relief Waterproof & Fogproof Fits Pentax Spotting Scopes Pentax premium spotting scopes adhere to the American standard of 1. 25" eyepiece thread diameter, facilitating the use of eyepieces from independent manufacturers. That also means, of course, that the wonderful Pentax eyepieces can be used in other telescopes and spotting scopes which accept 1. 25" eyepieces. Pentax eyepieces are a near consensus choice