Received the product today and been using for about 4 hours now. No ear fatigue, very comfortable in ears. Slim enough to lie on the side. Sound reproduction and soundstage are awesome, every detail is hearable. In search of a perfect sound I have explored numerous Chi-Fi iems with multiple DD and BA drivers like TRN VX, KZ Castor, but a single Sennheiser driver beats them all. Sounds great, fits perfect, the part behind your ear is flexible with a firm wire inside, you can adjust it to fit better. The adjustable ear tip position does affect bass, you may choose to your liking. What I dislike about the product is its cable. The part just next to a jack protecting cable from bending, and the sliding part where the cable is "Y"-split are just pieces of heat-shrink tubing.