でーたしーと
http://www.etymotic.com/downloads/dl/file/id/700/product/359/er4sr_er4xr_data_sheet.pdf
http://www.etymotic.com/downloads/dl/file/id/691/product/359/er4xr_er4sr_user_manual.pdf
SR
https://www.seeko.co.kr/zboard4/data/forum_etc2_1/_20160503_004214.JPG
XR
https://www.seeko.co.kr/zboard4/data/forum_etc2_1/_20160503_002213.JPG