Evans Tri-Center heads are made of a polyester base that prevents detuning caused by humidity. The tri-centered dot in the center of the head eliminates unwanted overtones, and also adds weight to the center of the head, giving it a lower fundamental tone. The laser-cut collar is designed to give you a proper fit and helps with even tuning. The head also feels similar to the rawhide versions because of a micro-textured finish. This is the perfect head for marching bands, drum corps, and any other musicians who want to play congas or bongos outside.