Named for the Latin word for butterfly, PENTAX Papilio 8.5x21 binoculars are the perfect choice for insect observation in the field and in museums and galleries. The enhanced observation capability of the Papilio binoculars is made possible by a PENTAX Convergent Lens Optical System Engineering (CLOSE) mechanism. The CLOSE mechanism automatically slides the left and right objective lenses toward the center when the focus is fixed at a short distance. Fast and easy center focusing for handling ease Helicoid eyepiece rings for extra viewing comfort Fully multi-coated optics to eliminate harmful ultraviolet rays while improving light transmission for high contrast images with no glare or flare High quality BaK4 prisms transmit more light at the edges to enhance illumination for easier viewing in dim light.