1” traditional bell on one side for lower frequencies. Patented floating diaphragm on one side for higher frequencies. Non-chill rim and diaphragm. Anatomically designed headset. Durability is demonstrated by the fact that the headset can be reliably flexed one million times. Patient comfort is assured with when rubber versus metal is applied to your patient when using the nonchill rim and diaphragm. Three-year warranty on this product includes free repair, during this period, on any manufacturing or material defect(s) except in the cases of obvious abuse or accidental damage.