This is the standard pressure regulator that comes stock, in the 2012-21 SXF / XCF / EXC-F / XCF-W / FE / FE-S / FC / FX bikes.  It's a 3.5 bar or 50-52 psi regulator. You don't need to reconnect to the return hose if you don't want to, when changing out.  This will keep the bike making the same air/fuel ratio that it does as you have it now.  The high pressure one we have, will richen your air / fuel up about .5 a point. So if the bike is running at 14:1 now, the high pressure will change to 13.5 :1.  This isn't reccomended for most bikes, but you can change them and use as a tuning aid.

Standard pressure fuel regulator for 12-21 / 250-501