Over the years, the government has tried to streamline airport security and cut down on long lines and complaints. Elderly passengers and children may go through security screenings without taking off any clothing. Pre-screening program at 20 US airports allows approved passengers to keep on their shoes, belt or jackets and does not require laptops and toiletries to be removed from carry-on baggage. The growing use of full-body scanners also allows travelers to go through security lines faster. Despite the frustration caused by passengers having to remove their footwear at security checks the US Transportation Security Administration (TSA) has abandoned shoe scanning devices meantime. They found after extensive testing the current level of technology is unable to detect all of the various chemical compounds (liquids and gels) used as explosives.