Heat shrink tubing that won't hold its seal costs you time and creates callbacks on wiring jobs that should have been done clean. You re-do it or you leave a connection that fails later — neither outcome is acceptable when you're billing by the hour on a commercial rough-in. This 4-inch heat shrink tubing shrinks to a tight, waterproof seal when heated — the polyolefin composition wraps around the wire bundle and locks out moisture, corrosion, and vibration. The 2:1 shrink ratio covers multiple wire gauges without needing different sizes. Black color blends into standard wire bundles for a clean finished look. Standard on electrical crews running wire from panel to fixture across northeast Nebraska and northwest Iowa — it's the quick-seal solution when you need to insulate and protect with Stocked at Crofton Lumber and Akron Lumber.