There's a thread about the Hobbit rad-cals that may explain them a bit better than I can, plus a video in the link. If I could sum them up, I'd call them super high resolution printed cabinet art decals with a nice glossy laminate like finish.

https://pinside.com/pinball/forum/topic/jjp-new-decals-called-rad-cal

FWIW I thought Radcals were pure gimmick when first announced. My Hobbit doesn't have them. However, I was able to see in person recently two Hobbit LEs side by side, same everything except one was Radcals and one regular and I must say they do look pretty cool up close.

Considering how much nicer they look than standard replacement decal sets for other games which average around $300, rad-cals aren't really much more expensive in that regard, plus the enhanced art really does look amazing.

while they can be installed later, the $400 charge includes installation at the factory. If you were going to do it, then I would do it at the factory. The Hobbit LE that i delivered down your way last week had them installed and they do look great.