Leupold Cascades Internal Focus Porro Prism Binoculars touts a focusing system that has no moving parts which makes them more rudded and waterproof. They have coated optics for excellent clarity and light transmission.  Cascades have an exceptional focal range, an object can be focused on as close as 10 feet away.  This performance makes a great combination for birding and bird watching.  Leupold Cascades binoculars are covered by the Leupold Limited Lifetime Warranty.