You can download it for free from the WinRAR website. Using it for free is a whole other matter, which involves software piracy that is against the rules to discuss here.
However, there is the free 7-Zip program which can read RAR archives. Not sure if 7-Zip is being actively maintained anymore, but it's probably your best free AND legal option regardless.
Light bulbs you shouldn't buy
There are plenty of dimmable LED light bulbs, but make sure you don't buy the ones that flicker when you dial them down.