Sennheiser CX 150 earphones are low to mid range in ear headphones. I was recommended them in a shop as being the best available on the market for the price and that they are not much different to far more expensive in ear headphones in terms of quality, so gave them a try and have not been disappointed.
The set itself is discrete and small. They are black and functional in design. The ear piece comes with 3 different pad sizes to fit all ears. These are black and pretty standardised so the fit is as good as on any other similar set. I personally find them to be very comfortable in the ear (particularly compared to the flat fronted cheaper ear pieces available). The pads are very easily interchangeable and when on they stay on well. I have found with other models that the pads can come off easily if you keep them in your pocket or bag and you lose them but this doesn't seem to be the case here.
The overall design is functional rather than sleek. The diameter of the ear piece is around 1cm and it's shape is spherical. On the portion of it that sits outside of the ear there is a handy grey 'handle' so they are easy to remove. It's not pretty but discrete and a nice touch, although I find that my clumsy fingers find it quite hard to get a good purchase on it and it often slips out. Perhaps it could have been a little larger to make for easier removal but it's not a major criticism.
The output for the headphones is a standard mini jack and there were not any other options available to convert it. As these are mainly designed for use on the move with portable devices I don't see this as an issue. The cable is black and of a good length of about a meter so you can have your playing device in a pocket or bag and the headphone will still reach your ear without any pull or discomfort.
As for the sound quality itself, for me this is very good given the price of the unit and that they are in ear rather than full headphones. I have found the sound quality to be very full and have great clarity. They don't struggle with too much bass, an issue I have had elsewhere where the sound crackles and they don't peak or crack at high volumes. They also don't have the tinny quality some others have and generally offer a very dynamic sound. There is good clarity on instrumentation as well when listening to music where alot of things are going on.
They have excellent durability as you would expect from Sennheiser. I've had these headphones now for well over a year and not experienced any issues with them. They get used daily and get bashed about in my bag or pocket but haven't let me down. The sound is as good as when I bought them and there is no cosmetic damage despite the mistreatment.
If you wear the right size pad for your ear then the noise cancelling is also pretty decent. It doesn't totally cancel out external noise but does enough to give the music or whatever you are listening to more clarity.
Given the price of £15 (reduced from £19.99) when I bought them it's hard to flaw them. I'm sure for purists there are better out there but for everyday use thy are an excellent quality earphone and well worth the purchase