Abstract: An improved tobacco smoke filter is provided with a novel arrangement of restricted passageways and expansion chambers which entrains the smoke so that greater diffusion thereof occurs in a first expansion chamber and greater and more efficient mixing with the ambient air occurs in a second expansion chamber than was previously possible in prior art devices, so that more tar and nicotine are removed and greater cooling of the smoke is provided. Indexing and indicating means are provided on the device so that the operator thereof may easily select the amount of ambient air desired for admission into the second expansion chamber.