Remember to use the same measuring units, eyepieces are generally sold by their focal length in millimeters, telescopes are often sold by their focal lengths in centimeters or inches.
(eyepieces; are generally sold; by their focal length in millimeters) (telescopes; are sold; by their focal lengths in centimeters or inches; T:often)
eyepieces telescopes
are generally sold are sold
by their focal length in millimeters
by their focal lengths in centimeters or inches T:often