Halex Company | sku: 320684575 Halex 1/2 in. Knock-Out Seal Knock-Out Seals are designed to cover exposed knock-out holes in steel boxes and other metal enclosures. The 1/2 in. Knock-Out Seal offers corrosion resistance. It is convenient and easy to use.|Covers knock-out holes in metal enclosures|Zinc-plated... Log in for pricing