MP3/FM Radio Sunglasses 4GB Memory Absolute music freedom with no wires or cords to dangle or tangle. Store up to 4000 songs on the 4GB flash memory. Built-in Lithium Ion Polymer Rechargeable Battery for long playback time. Polarized lens material to filter out 100% of all UVA, UVB, UVC and harmful blue light. The high quality speakers with three directions of movement for precise positioning.