Canon IS Binoculars Dioper Lock

I love Canon's IS 10x42 binoculars but there is one annoying flaw in their design. The diopter for matching focus on each optic is very easily moved. This necessitates a recalibration of the optic to get a sharply focused binocular view. This simple model prevents this from happening. The sleeve just fits over the diopter eyepiece barrel. You could make a different size for whatever Canon IS binocular you have.