A poster saying "Stools for rent" is seen on the window of a store outside the Expo Garden.

Forget Haibao mascots, souvenirs from national pavilions or the ever-popular Expo passports - the latest hot-ticket item at the Expo 2010 Shanghai is a small folding stool, available for just 10 yuan ($1.5).

With the notoriously long lines at popular pavilions and growing crowds fighting for space inside the Expo Garden, the stools are a cheap and portable option for visitors who want to sit down and rest from time to time.

Xie Hao, a visitor from Beijing, said it was only natural for the plastic folding stools to become so popular.

"Big events usually promote sales of certain products, making them popular," said Xie. "At the Expo, it's the light and handy stool."

Often seen at the long queues outside pavilions, the colorful stool offers visitors a few inches of space for resting on hot days.

Even passengers on the Metro have been spotted sitting on them.

"It is a necessary item for Expo visitors and it has a unique personality in terms of design. The stool itself can be an interesting souvenir as well," said a visitor surnamed Jin.

Each of her friends had a stool as well.

The popularity of the stools has made 40-year-old Sun Wei and his younger brother Sun Qiang two of the busiest vendors outside the Expo Garden.

The Sun brothers have been selling the stools and other Expo souvenirs since May 1.

"The stool is definitely a bestseller. I sell at least 120 to 180 (stools) per day in the area opposite Gate 5. My brother, who's a mobile vendor, sells more," said Sun Wei.

With a monthly profit of 5,000 to 6,000 yuan each, the brothers said they talked to the official Expo-licensed shop about sponsoring the stool. "They're not interested at all, regardless of the huge demand," said Sun Wei.

A staff member surnamed Xu from the Expo franchise shop said the stool is not on the list of official Expo-licensed products.

The stool is only available outside the Expo Garden. Most visitors get their stools from independent vendors like Sun, online or from their companies as gifts.

Plastic manufacturers located around Shanghai, in cities in Zhejiang province, including Jinhua, Wenzhou, Taizhou, Nantong and Huangyan, have received multiple orders for the stools since May.

"We started producing this kind of plastic stool in 2005, but have never seen it sell this well," said Pan Lingping from Jiaxin Plastic Co Ltd in Huangyan.

It isn't just manufacturers in nearby cities looking to profit from the Expo. Bazhou in Hebei province, which is 1,200 km from Shanghai, has its teeth sunk into a piece of the Expo pie. Bazhou is famous for small private enterprises manufacturing plastic goods.

"Our output has increased four or five times compared with the same time last year and about 90 percent of our total production goes to Shanghai," said Wang Minxue, a manager of a factory with 10 workers. "We produce about 700 to 800 folding stools by running all four machines eight hours a day."

Zhang Junbiao, another manager of a plastic factory in Bazhou, said he has to get all of his seven workers to put in extra shifts due to the overwhelming orders coming from Shanghai.