Most tanning beds are horizontal enclosures with a bench and canopy (lid) that house long, low-pressure fluorescent bulbs (100–200 watt) under an acrylic surface. The tanner is surrounded by bulbs when the canopy is closed. Modern tanning beds emit mostly UVA (the sun emits around 95% UVA and 5% UVB). One review of studies found that the UVB irradiance of beds was on average lower than the summer sun at latitudes 37°S to 35°N, but that UVA irradiance was on average much higher.