An open (sometimes referred to as "open aire" headphone is one that uses some external airspace to reproduce life-like audio within the ear-cup. Think of it as having premium speakers next to your ears that you can control the volume for with extreme precision. The trade-off is that at extreme volumes some sound will leak out. Our "open aire" wireless headphone models include the RS 120 and RS 180 and RS 185.
A closed headphone isolates you from your environment and vice-versa (ie: the sound is contained within the headphones). This is perfect for critical listening or a situation where you do not want to disturb/be disturbed. Our "closed" wireless headphone models include the RS 160 and RS 165 and RS 170 and RS 175.
With Sennheiser headphones the audio will always be accurate and responsive and is sure to please no matter what situation you need headphones for so it is personal preference as to whether "open" or "closed" headphones are used.