You will get 20 pack headphones bulk which can be used in schools, classrooms, airports, etc. Headphones for class set is not easy to break, the L-shape jack design makes the jack stronger and not easy to be damaged, the 3.5mm jack can be adapted to your pad, phones, computers and other devices The classroom headphones is only 1.69 ounces, and the soft earcups , so you won't feel uncomfortable even if you wear them for a long time The bulk headphones for Classroom can be rotated 90° for easy storage and better fit your ears TJZXGUI Service: One year warranty,if you have any questions,please contact us,we will solve for you soon and give you the most satisfying reply