20 Pieces Foam Stopper Plastic Foam Plug 50mm Openings for Tubes and Flasks, Beer Making, Yeast Starter

These are meant to be flask stoppers, but I've actually bought these to use as speaker port plugs.They do come vacuum sealed, I opened the bag and left them in there for a couple days - by the time I was ready to use them they had perfectly returned to their intended shape. May require a bit of patience, but they do bounce back!The 2" diameter and soft foam is a great fit across multiple bookshelf speakers! Using my speakers with a subwoofer so decided to plug the LCR ports as I didn't need the bass extension and a flatter response curve is never a bad thing.These fit perfectly in my Triangle HiFi Borea BR03, BR02, and BRC1 and helped tighten up the mids while getting rid of some of the bass response (unwanted, in my case).

Arrived as promised. nice product.

they’re good they fit. They’re just not very tightly sealed.

Used with an urlenmyer flask and magnetic stirrer for beer starters.

Any resemblance between these items and foam stoppers for flasks is purely coincidental. These are crap. Not even worth sending them back.

These do a great job keeping a flask ffee of contamination through autoclave and culturing in a shaker.They can be reused a few times but only on a flask with the same size or smaller mouth as they keep the shape of the flask opening once autoclaved but still seal pretty tightly to the glass.

Just what I was looking for!

I don't know why I've been cleaning and hanging on to the same two foam stoppers for so long. Perfect fit to flask.