Starting at the Pike level RockShox these should be included with your Levo. They are called Bottomless Tokens or Air Volume Reducers. What do they do ? Strictly speaking they take up room in your shock (the one with the air valve under the cap) which gives you a more progressive shock for more aggressive riding – put differently, it lessens the chance that you will bottom out your fork/shocks. Your front shocks are not the same on each side, as these are inserted in the “air” side.
If you find your front end o-ring at the top of your travel you may want to install one. It’s pretty simple.
This guy explains how to do this operation in his badly lit workshop, with many camera angles…