United Scientific RSTPK2 Premium Laboratory Black Rubber Stoppers | Good to Seal Bottles, Tubes and Many Other Containers - Black Lab Plug | #00 to #7 Assorted Sizes | 1LB of Stoppers

They are rubber corks meant for science, but we used them for something different. In building a portable solar generator (DIY Goal Zero Yeti 400) I was trying to find a way to secure the bettery inside of the plastic ammo box used for the generator housing to attach everything to and needed a way to protect the battery from the screws protruding in from attaching things to the outside of the box.I screwed the charge controller and inverter on opposite sides of the box and used these rubber pieces to screw onto the back of the pointy end of the screw inside the box.This worked great not only to protect the battery from the screws, but they also happened to be the exact right size to where the battery slips in the box, snuggly right between the rubber bumpers with no modification using a 396wh battery.Sometimes you need to think outside the box and this worked perfectly for what I needed them for!

This is a great product but the description says 1 pound/ 50 count bag of stoppers. It doesn’t say 1 pound OR 50 count. Received 36 stoppers.

Works great. I used it for an object lesson experiment with a flask and filter. I gave it 4 stars only because I only needed one stopper but couldn’t find it in smaller quantities.

Used these to plug holes in a tank while cleaning it. Good variety of sizes, rubber flexible, excellent value

Good quality stoppers. Very nice. Good assortment. I bought three different brands and these were the best of the batch. Don't let anything ~stop~ you from buying these. ;)

Good variety of sizes, however only received 35 stoppers when the description said 50.

I couldn't believe how many stoppers and how many different sizes that I received for such a reasonable price. They did a great job on the project which I was doing.

Delivery was fine, no damage. The only thing was I was looking for a smaller size stopper, but Now I have a good selection for other applications.