HamiltonBuhl Primo Headphones (100-Pack)Teachers find that students excel, when they are more focused on their lessons, in classrooms, labs, libraries, and testing environments. Primo headphones are uniquely designed to provide the perfect blend of all of these. Noise reducing ear cups allow students to clearly hear their lessons, protected from unnecessary and distracting ambient noise. Made of ABS plastic, with the exclusive chew, kink and knot resistant Dura Cord, and 3. 5mm stereo plug,