not sure why , give Sennheiser 's reputation for \* high quality \* product , but the \* buzz \* from \* two different set of headphone \* for my Sennheiser HDR 180 , along with the r 170 backup headset I get really annoy I !! come to find out after wonder why , I twist off the removable earcup -lrb- use to access the battery -rrb- and both the r 180 \* and \* the r 170 have distort diaphragm ! they do not even play that loud , so what be with the low quality ?? pro : + the wireless function actually work con : - pay too much - listen too little - disappointed too much ! verdict : I be return the whole thing plus extra r 170 headphone , not worth the hassle !