End hose Standard Length 3Meter

Why the concrete pump end hose standard length is 3meter? 
According to the construction experiences and concrete pump truck design.the end hose is 3meter in standard. If too short,it is not convenient for operation,if too long,it would cause the arm shake and swing which is not safe for construction site. That’s why we produce and sell out thousands of 3meter end hose every month.

But for some countries,they do use the 4meter length end hose.it depends on peoples operation hobby and prefer.

We offer Dn125 5inch end hose from 1meter to 9meter. 
2meter end hose is designed for spider concrete pump placing booms, 
3meter 4meter end hose is designed for concrete pump truck cars,trailer pumps.

Other length 4meter -9meter is designed for long spiral drilling rig pilling machines.