Compatible: The inner diameter of the telescopes eyepiece eyecup is 22mm / 0.87in, suitable for microscope eyepieces, monoculars and binoculars of 42-48mm / 1.65-1.89in Protect Your Eyes: Telescopes eyepiece eyecup helps to establish a perfect distance between eyes and tentacles Protect your microscope eyepieces and your eyes Excellent Performance: The telescopes eyepiece glasses can provide better observation effect without interference from external light sources Reduce shock and better protect your eyes : The telescopes eyepiece glasses have undergone strict testing and have stable performance, so you can : The telescopes eyepiece eyecup is rubber, which is foldable, wear-resistant, sturdy, not easy to damage, and practical