This is the super handy stuff for all kinds of sealing and cushioning jobs! It's black neoprene sponge rubber cord, also called O-ring cord. It's highly compressible, which makes it perfect for creating custom gaskets, weather stripping, door seals, padding for toolboxes, or even craft projects. We've got it in a range of diameters: 3mm, 4mm, 5mm, 6mm, 7mm, and 8mm – just let us know which size you need. Made in the United Kingdom by The Seal Extrusion Company, so it's good quality. You buy it by the length. Brand new and ready to ship. Whether you're fixing a leaky window, sealing an enclosure, or making something vibration-proof, this flexible cord is your go-to solution. Easy to cut and glue in place!