With polarized carbonic lenses, Smiths Interlock Trace Sunglasses make a day out on the water easier on your eyes. If youre not water-bound, change your lenses using these shades new INTERLOCK Interchange system. Simply twist the temple arm to open the frame a crack, switch lenses, and twist the arm back for a secure close. The Interlock Trace Sunglasses strong, flexible frame survives your bike rides and summer hikes, and comfortable temple pads wont create a brain-squeeze. The Interlock Traces rectangular lens shape provides coverage on bright, sunny days. See sizing chart for list of interchangeable lenses.