I ordered 4 different Cando flexible hand bars: red (light), green(medium), blue(heavy), and black(x-heavy). All four colors felt about the same. To check my sense of feel I measured the force required to bend the bars to 90 degrees. The forces were as follows: red- 10.2 lb, green- 8.2lb, blue- 11.2lb, black- 10.4lb. The Cando bars appear to be trying to compete with the There-Band "Flexbar", which come in three colors and stiffnesses red(light), green(mid), and blue(heavy). Using my measurements the force to bend these bars 90 degrees are red- 2.3lb, green- 4.3lb, blue- 6.5lb. I am using the bars to do "eccentric" contraction exercises for tennis elbow. I find the green Flexbar good for me. All the Cando bars are too stiff. It is clear to me that there is no concern about quality by the makers of the Cando bar. How else could one explain that a "light" red bar having about the same stiffness as a black "x-heavy" bar.