It's the double deluxe side mount.

The long 1.5 x 3 profile is extended from 21 inches to 23 inches.

The 1.5 x 1.5 support upright profile has been extended from 14 to 16 inches.

2 more cross profiles have been added to mount a second shifter/handbrake/flight gear.

the entire side mount has been reinforced with an additional 2 brackets to handle your extra gear.

Includes:

everything in the Phantom Deluxe Side Mount and:

2 extra cross profiles 9 inches

6 extra corner brackets.