Sun-dried cotton combined with green notes, white flowers, and a hint of lemon. Never run out of your favorite Yankee Candle fragrance when youre on the road. Smart Scent Vent Clips have a clear window so you can easily see when a replacement is due. (Note: you may see a small amount of liquid residue at the bottom of the window when the fragrance is depleted.) The odor-neutralizing unit fastens securely to any vehicles dash vents. The fragrance is released as air flows from the vents. Smart Scent Vent Clips work optimally in temperatures of 70F or above flowing from the vent. You may adjust the strength of the fragrance using the slider on the back of the clip.