Bell Mach MIPS-Equipped MTB Helmet - 2016 L/XL BLACK/RED/SILVER New rounded shape looks and feels smaller. Larger vents keep you cool on hot days. ErgoDial Fit System offers fast, easy adjustment. Extended In-Mold Polycarbonate Shell MIPS (Multi-Directional Impact Protection System) MIPS is a low friction layer between the shell and the liner which allows the helmet to slide relative to the head in certain crash scenarios