Walk-through explosive and metal detectors are archway systems that use electromagnetic or microwave technology to screen passengers for weapons and explosives in high-traffic locations such as airports. Hand-held detectors, such as metal wands and explosive trace devices (ETDs), provide portable, targeted screening with X-ray and chemical analysis capabilities. Desktop detectors use technologies such as chemiluminescence to examine swabs from surfaces or goods for explosive traces, making them appropriate for use at stationary checkpoints.