The Photek Add-On Background Crossbar Kit contains one set of the SO-4023-4 crossbar kit and two background add-on plates. This will allow you to use two backgrounds on one S4010-4 background support system.
The two background add-on plates simply slide over the existing stud on the SO-4010 stands, and you tighten the locking screws. The plates have an additional stud for mounting the second crossbar kit.
Assemble the SO-4023-4 crossbar supplied and install a second 8x12 foot background. Slide the new crossbar with the background installed over the stud on both ends and your'e all set.