In the months leading up to the eclipse, many counterfeit glasses were put up for sale. Effective eclipse glasses must not only block most visible light, but most UV and infrared light as well. For visible light, the user should only be able to see the Sun, sunglint reflected off shiny metal, halogen bulbs, the filament in unfrosted incandescent bulbs, and similarly intense sources. Determining whether the glasses effectively block enough UV and infrared light requires the use of spectrophotometer, which is a rather expensive piece of lab equipment.