Dimplex’s ^Opti-Myst® fireplace insert features revolutionary ultrasonic technology that uses steam to create impressive flame and smoke effects. The results are so realistic, you’d think it was a real wood-burning fireplace. As steam is released from the bed of baises, light reflects off the water molecules, creating a convincing visual effect of cold flames and smoke. Each fireplace features an easy-to-fill water tank that provides 12 to 14 hours of continuous operation. Optional: replace logs with river pebbles.