Not sure exactly which binocular this eyeguard belongs to. The internal threading diameter that would fit to your eyepiece is 30.3mm. The outside diameter of the eyeguard is 40mm with an opening of 19mm diameter. It is 9mm wide. Have been in storage for some time. Save when buying 10 or more! One of our customers advises that this is an original B&L eyeguard that fits the Mark 1 and Mark 2 military binoculars. Thanks David.