Plumbers and DIYers, this is a handy pack of 12 brass compression sleeve ferrules – sometimes called olives or barrel rings. They have a 4mm internal diameter (ID) and are made from soft copper, which makes them easy to compress for a tight, leak-free seal in compression fittings. The brand is Super Crown, and they're brand new in the original packaging. Made in Taiwan, which is known for decent quality hardware. The MPN is SCCB0032. These little rings are essential when you're connecting copper, plastic, or sometimes even steel tubing using compression nuts. Having a pack of 12 means you've got spares for multiple jobs or can do a whole plumbing project without running out. No UPC applies. If you're fixing a leak under the sink, installing a new water line, or working on anything with compression fittings, having the right size ferrule is key. This pack takes the guesswork out and gives you reliable parts to work with.