Bell Blitz MIPS-Equipped MTB Helmet - 2016 New rounded shape looks and feels smaller. Large vents keep you cool on hot days. ErgoDial Fit System offers fast, easy adjustment. Snap-in removable visor ensures you'll see what's ahead in bright trail conditions. MIPS (Multi-Directional Impact Protection System), a low friction layer between the shell and the liner which allows the helmet to slide relative to the head in certain crash scenarios.