If you do any riding in the dark or gloom, or rain....
I'm a big fan of adding some kind of extra red lights at the rear of yourself.
It's a bonus if they add more lights when you brake, like this Bestem top case.
I'm no electrical whizz - but i managed to tie in the top case lights with my LIKE's running light and brake light. You just need access to the wiring of your rear light.
There are a couple of DIY posts here on the install of this case.
(also - a lighted Bestem is about 1/4th the price of some cases; where lights are extra and the rack is extra)
Stig