Smiths Aerospace support director for Asia Pacific David Whithers walks through the company's Sentinel, a non-evasive airport screening device that detects explosives and illicit drugs by blowing air on those who pass through and then sampling for particles, at Asian Aerospace in Singapore March 1, 2002. The device, which sells for $200,000, is among a handful of technology on display at the Singapore air show that has generated greater interest in the aftermath of the September 11 air attacks in the United States.