The holders are made a lightweight flexible foam so it form fits the smoker's nostril. It is non-reactive with the heat of a cigarette even when smoked to within 1/8th of an inch of the holder.

It weighs very little so it stays in the nostril without assistance. Of course there are a lot of different nostril sizes so I can't speak for everyone.

It is hands free - when you want to ask you tab the side of your nose while over an ashtray or you can pick up an ashtray the tap the cigarette on it.

I don't block the other nostril to drag. What I do is smoke unfiltered Pall Mall or Camels in it so that their is enough smoke when diluted with the other nostril. Unfiltered cigs have an easier draw.

I also like the little flavored cigars - it's like nasal incense.

I also just breath normally with my mouth open and a nice amount of smoke comes in with each breath.

The smoke is not hot at all and I can tell you that I've been using this daily for a year and have not had any sinus problems or loss of sense of smell. Actually it's made my sinuses clearer!