With the Smith Interlock Whisper Sunglasses, you wont be wrestling around and cursing under your breath when you change your lenses. Smiths new INTERLOCK Interchange system makes switching out these polarized lenses a breeze. Just twist the Interlock Whisper Sunglasses temple arm to open the front of the frame a sliver, switch lenses, and twist the arm back for a secure close. The Polarized Carbonic lenses cut down on glare, and the Interlock Whisper shades durable frame works well for winter and summer sports, along with casual trips around town. See sizing chart for list of interchangeable lenses.