Constructed of high quality 3mm thick neoprene/nylon laminate, the Scopecoat Holographic & Electronic safeguards your optics from dust, dirt, dings, scratches and moisture. It is extremely water resistant and draws moisture and condensation away from your optic. This slim fit cover is perfect for the field. You may make it temporarily waterproof with commercial spray-on water repellent, and it is machine washable. This model is black, Size 5, which is 5.1 long x 38mm. It is compatible with Aimpoint Compact M2 and M3.