Need to boost oxygen in your aquarium or hydroponic system? These Quickun cylinder air stones are awesome! They create incredibly tiny, dense bubbles that dissolve way more oxygen into the water compared to basic stones. Seriously, they make your tank look like a magical bubbly fairyland. Each one is 2.28 inches tall and fits standard 3/16 inch (4mm) air tubing. They work best with a 2W to 4W air pump, and they're made from non-toxic, safe material that won't harm your fish or plants. They do need a little cleaning with a brush every few weeks or months to keep them from clogging up, but that's normal for any air stone. You get 2 in the pack, perfect for running multiple setups or having a spare ready to go. Super easy to set up – just attach your airline and you're good to bubble!