That’s a Pipe Repair Clamp / Pipe Sleeve Clamp
It’s also called a leak repair clamp or pipe coupling band.
What it’s used for:
This is used to quickly repair and seal leaks or cracks in pipes without having to cut the pipe or shut down the whole system for welding.
How it works:
1. Outer shell: Stainless steel band - gives strength and holds pressure
2. Inner gasket: Black rubber with the grid pattern - creates the watertight seal around the pipe
3. Bolts: You tighten the bolts to clamp it around the pipe and compress the rubber gasket