Dr Plumbs Meerschaum Lined Briar Pipes:
The Dr Plumb Meerschaum lined is a British quality light Briar pipe, which has been lined with Meerschaum. Meerschaum is a porous clay, which has excellent smoking properties as the clay absorbs moisture and allows more air to the Tobacco. This results in a drier, cleaner and smoother smoke. The Meerschaum also doesn't burn so there is no need for reaming or breaking in the pipe. The problem with Meerschaum is that it is fragile so if dropped it will break so they tend to be smoked at home.
So the next best thing is Meerschaum lining. This gives the same smoking properties but the Meerschaum is protected by an outer layer or Briar, which many also find more aesthetically pleasing.