Maybe the word "Ya Dom" is strange for you, but once you land to Thailand you will see many people are using it. Ya Dom is a kind of medicine that helps people to be conscious when they are extremely tired or out of concentrate.
It is an inhalers most Thai people use in their daily life, it had various shapes and sizes and has various brands. This is Thai traditional medicine around from 2,500 years ago and it made from the roots of ya dom.
It makes feel refresh so many drivers use it. Many foreigners are also buying this from Thailand as souvenirs and for gift for their friends as well.