China's national saluting artillery unit. [Photo/81.cn]

Three seconds is the time it takes three officers from China's saluting artillery unit finish a gun salute.

It takes a national flag raiser 15 seconds to complete a set of flag-raising movements.

A national motorcycle escort member should ride at 120 km/h during a mission on expressways.

These photos show China's four special national armed police units. The four units include the national saluting artillery unit, the national flag escort, the Snow Leopard Commando Unit, and the national motorcycle escort.

The national saluting artillery unit must fire their guns in sync with a national anthem. When a national anthem ends, the guns have to stop firing. Since different countries' national anthems have different time lengths, officers have to calculate the exact time intervals when they receive a mission.

A national flag escort lives in barracks to the east of Wumen Gate at the Palace Museum. The officers have to march out from Tiananmen Tower twice a day to finish their mission of raising and lowering the national flag.

The Snow Leopard Commando Unit only accepts applicants who have served in the armed police for one or two years. The officers have to undergo a series of interviews and physical and psychological tests. When someone is selected, they still have to undergo an arduous period of physical training, special driving lessons, and weapons training.

The most challenging training for national motorcycle escort officers is to push the motorcycles. A motorcycle weighs 265 kilograms. Pushing motorcycles and running five kilometers is a daily training routine for the officers. When carrying out a mission, the motorcycle officers have to meet strict speed requirements. The speed should reach 110 km/h on expressways, 70 km/h in the city, and 40-60 km/h when turning. During a military parade, the speed should be kept at 10 km/h.