These foam cylinders are super dense! More so than anticipated, which is a good thing for durability and high floatation. Purchased specifically for experimental mouse patterns in 3/4" size, these foam cylinders are exactly what was needed for them. I modified the cylinders by cutting them to shape, 1 cylinder dulled a razor blade, that's how dense the foam is! The finished mouse flies with these cylinders kept floating even after being chewed on by fish and weighted down with other water absorbing materials. I'm very impressed with this product, I will be buying more...