Shanghai Zhang Xiaoquan on East Nanjing Road.

The golden, shining products are very popular among locals, and people even line up in front of the store during winter to buy one.

"Especially during the second half of 2012, when up to 300 tangpozi were sold in a single day, and sales revenues of tangpozi alone exceeded 3 million yuan ($487,800) per month."

Tangpozi is so popular that the supply can hardly meet the demand during the peak time. After all, every tangpozi is made by hand.

But the durable tangpozi also has its "weakness" for the producer, because each one is so durable, it does not need to be replaced for several years. "Our sales stabilized to 2 million yuan this year," Qian says.

The round and shiny tangpozi is only one of the more than 200 kinds of products sold at Shanghai Zhang Xiaoquan, which is located on the city's busiest East Nanjing Road.

Like the store name implies, it is a specialist of knives and scissors.