This lens cap is for optical instrument (eg. binoculars, telescopes and spotting scopes).
Internal Diameter: 71mm (Note: the size is measured as internal diameter of the cap, which is equivalent to the external diameter of the lens including the lens housing).
Depth: 14mm
Material: Rubber.
Note: This listing is for ONE lens cap as described above (not for a pair). The cap is made of rubber material which is flexible. For this feature, the cap can normally accommodate lenses with slightly bigger diameters. For example. this cap can cover lenses with external diameter from 71mm up to around 73mm.

Note: The size of the lens cap is measured as Internal Diameter of the cap, which is equivalent to the external diameter of the lens including lens housing (as shown in the picture above). Please allow a small difference in measurement (eg. 0.5-1mm). A rubber cap can normally fit a slightly bigger lens than the specified size (eg. +1mm to 2mm depending on actual size).
If a cap is slightly bigger than the external diameter of the lens housing and there is no matched cap size available for the lens, you may consider putting an adhesive cloth tape around the internal edge/rim of the cap. This can often secure the cap on the lens.