Usually, roller handle has two style: EU style and US style. Eu style has one rod, is suit for Europe area and Australia market mainly, some other countries also use it. US style has two kinds of cage, 4 cages and 5 cages. It’s popular in USA, Canada and other North America area, South America area and so on.
The rod has two treatments, Zinc plated and Chrome plated. Chrome plated is better, Zinc plated is economic. Rod has two diameters, 5.7 mm and 7.7 mm. 7.7 mm is stronger, but 5.7 mm size is enough for normal projects.