Wall mounts are pre designed to add on to without moving the 2 arm supports on the original unit. Move the front support joist over 1 set of mounting holes and add on the next support joist and wall angle arm.
Specs-
Front Support Joist- 2"x 4"x 48"
Flat Wall Mount- 16"x 3 1/2"
Angle Brace- 1"x 1"x 14g
Arm- 2"x 4"x 14g
Mounting Plate to Joist- 4"x 7"
Proudly Made in the USA