1990 Lexus LS 400

Checking my fuses I notice the 40A AIRSUS fuse missing from the engine compartment (the middle of three to the right of the larger fuse block). Hasn't had one since I bought it two years ago.
Nevertheless, I want to get the fuse replaced.
I cannot find any info on what it's for and am curious how it would be missing in the first place?

Can I buy a new 40A fuse and install it myself - or - do I have to take it to the shop?
There is a large Toyota dealer in town - would I need to buy it there or can I go to a parts store instead?

Thanks!

 

it's for the factory air suspension.
if you dont have airsusp then you dont need it.

 

Thank you! appreciate it!