I bought my DSP 400s over 2 years ago and they have been in almost daily use. The sound quality is a big improvement over the conventional phones I used previously and the noise canceling facility has been very useful, allowing conversations to be made in noisy environments. The phones are light and comfortable to use for long periods. Unlike other reviewers here I find they sit securely on my head. I recently contacted Plantronics to find where I could buy replacement ear pads as mine were falling apart, as they will inevitably do with prolonged use. The reseller they directed me to did not stock the part so Plantronics sent me 3 sets free of charge. That is an exceptional level of service especially for a product that is not particularly expensive. A good product with excellent support.