Quad Arm for 4 LCD Monitor

Dual is for 2 pcs, quad for 4 pcs. It is a momentum that seems to run like this anyway.
For 2 sheets (12,980 yen)
http://donya.jp/everg/7.1/4547479479099/

For 4 sheets (19,980 yen)
http://donya.jp/everg/7.1/4547479479105/



The part of the arm looks like this




Are four environments to utilize day traders, graphic design, CAD related? What does not apply to four liquid crystal monitors even though it does not apply to any of that ...?

Because it increases work efficiency by about 30% with 2 sheets, if it is 4 pieces, at least 50% will be up ......