Well I have not had a check to try them ALL out but the one I tried works fine at 4.5V just not real loud though I did not take the sticker off and I am half deaf. .

 

It is totally ineffective with the seal on.
There is hardly a whimper with the seal still on.

 

My buzzer is AI-1223-TWT-5V-R

Digikey saysd says it is "magnetic" (I doubt it). Its datasheet does not show the polarity of its pins.

The E-Bay ones have no manufacturer's name, no part number and no datasheet.

Both have a fairly high frequency so I suspect they are piezo beepers.

 

I know this is an old thread, but the answer was not given so I'm going to lay in on you. The sticker's meaning suffers from an Engrish problem - that is, a humorous foreign mistranslation. The meaning is this: If you intend to wash/clean your project when you're done assembling it, leave the sticker on until after you're done with the cleaning. Removing the sticker prior to cleaning risks cleaning cleaning fluid (along with whatever sticky residue the cleaning fluid might be carrying) getting into the buzzer and affecting the sound.

 

Thanks Mr Chips. Better than the answer I thought of. I forgot that a lot of modern fluxes can be cleaned off with water.

They used to use a solvent that was safe for almost all plastics - they were banned in the hope that the ozone layer might recover.

Now all the production soldering uses water soluble fluxes so the boards can be washed in water - any components with exposed cavities have to be sealed to stop them filling with water.

 

I know this is an old thread, but the answer was not given so I'm going to lay in on you.

The answer was in post #3

 

The answer was in post #3

Did anyone mention zinc-air hearing aid batteries?

They have a pull off sticky tab to exclude air until you're ready to use them.

 

Also, beware of warranty issues around seals.