Having the use of both of your hands when diving with a light can make a big difference in the outcome of your dive objective, if you are searching for lobster on a night dive, or looking under rocks for tasty reef fish to fry in a skillet having both hands freeis a must! All Nite-Rider mounts are compatible with all Nite-Rider light heads. Helmet come in two sizes, lg-xlg and sm-med. We sell more of the larger size 4-1. Consider the thickness of your hood when ordering. In addition, it can be further adjusted by removing layers of foam.