http://www.thehumansolution.com/humanscale-m8-monitor-arm-sds.html
The Humanscale M8 Monitor Arm is an ideal solution for heavy monitor applications because it can support a wide array of monitors weighing anywhere from 8-42 pounds. Other high-capacity monitors arms have bulky designs that restrict their performance, but the Humanscale M8 Monitor Arm offers the best of both worlds: effortless adjustment and flawless ergonomic function.