Costa Slack Tide Polarized Sunglasses - Black Tortoise/Blue - When the tide goes slack, so does the fishing. In Costa’s athleisure Slack Tide sunglasses you can move on to another spot to chase a different adventure. This laidback west coast inspired frame is infused with functional elements - Hydrolite padding, pin hinge, ventilation and 580 Polarized, 100% UV Protection lenses so you can see through multiple tide changes.