Timoo Tornado Tube Bottle Connector Cyclone Tube for Scientific Experiment, 5 Colors, 10 Pieces

These are awful. I have been teaching for 25 years and made my own tornado tubes. Thought I'd buy these to save me time. Sure these look nice but they don't work. On every connector at least one end would slip off the bottle (not fit and yes I took the plastic cap ring off)). Tried several different bottles to make sure it was not the Pepsi bottles I was using. So maybe hot glue or super glue the connector to the bottle. Then one realizes the hole in the bottle is to small to get a vortex to create the tornado. Save your money, patience, and time - don't buy these.

I've tried several bottles and none so far fit these connectors. I bought them to use to create tornadoes. Not with these. Great quality though.

Didn't not fit 2 liter bottles water leaked

They don’t fit on average water bottles

Did not work well! Leaked all over the place. Not just one, several of them