【Measuring】Please measure the Outside diameter of the Ocular Lens outer tube's diameter to get accurate sizing, if the diameter is between 38.5-40.7mm, it will fit perfect. If the diameter is different, please choose a different size. 【Protection】These covers protect your lenses from rain, dust and scratches in any weather or environment. They also offer protection to your lenses in transit and storage. 【Easy to Remove / Add】Place the rainguard cover on the Ocular Lenses outer tubes to protect your lenses. You can conveniently attach to your binocular strap to keep within easy reach. 【Design】The high quality One piece flexible cover stretches for a tight fit. This ensures optimal protection for each Ocular lens. 【Fits Models】All the sizes we list allow you to find the correct size for all standard binoculars, monoculars and scopes. Compatible models include 8x30,10x30, 8x32, 10x32, 8x42,10x42, 8x50, 10x50, 8x56 and 10x56 models