They are particularly popular in Taiwan, South Korea, Russia and India, said Joyce Ho, sales manager at HiTop.
Matt Chen, a sales specialist at Forward Electronics, said the crowded roads of these countries led to more accidents and that's helped push adoption of the units. He also said they are gaining popularity in China, but not necessarily because of crowded streets.
"People's idea about the law isn't very clear there so they have accidents every day," he said.
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