Hoodman's Hoodeye Eyecup for Canon 22mm Eyepieces Models will help block out light when looking through your camera's viewfinder . From its over-sized design, which seals out ambient light, to its rotating nature that accommodates right or left eyed shooters, this eyecup ensures that the Canon 22mm eyepiece shooter can get their shot with ease. The self locking mount slides over the eyepiece mounting rails, keeping the cup in place. Additionally, the hypoallergenic silicon keeps irritation at bay for hours of comfortable shooting.