These rubber microscope eye guards have an inner diameter of 30mm (1.18 inch) mounting size.
The eye guards stretch slightly by 1-2 mm, to fit eyepieces with an outer diameter of approximately 30mm (1.18 inch).
The inner lip (6mm, 0.24 inch) holds the eye guard in place to prevent it from sliding down on the eyepieces.
They are foldable for different applications. One pair of eye guards contains 2 pieces.
PLEASE KINDLY NOTE: These eye guards are designed for microscope eyepieces, not binoculars. Please measure the outer diameter of your eyepiece. Other sizes are available for eyepieces of different outer diameters.