Product review (5 stars): Whistles at earsplitting levels when you blow air through it.
Good quality corrugated tube. Similar to the stuff wires are sometimes wrapped in, with no slit. But I bought it to build a miniature vacuum, and for some reason it screeches really loudly when you pull air through it. At first i thought it was my motor or something screeching, but eventually I took the whole thing apart and hooked a 2m length of it to the end of our regular vacuum cleaner. Well it was so loud it hurt my girlfriends ears (I was already wearing earmuffs due to my prior experiments). I found I could make an extremely loud whistle just by blowing through the tube with my mouth. I won't deduct any stars because any corrugated tube with these dimensions might do this, but just be warned if you want to use this for airflow applications.