What is this slot for?

[Crabby]

Thanks all, I should have figured it out by having a Denali before this with hud.

 

[B-train]

I looked in the manual and didn't see any info on that horizontal slot on the right of the start stop and inverter button or I missed it. Any ideas?

I used a similar slot on my 3500hd for business cards ans a gas card

 

[Crabby]

Good idea. I'll find some use for it.