Plumbing question

[GreenSpottedPuffer]

What kind of tubing (if thats what it is or called) have I seen people use on stuff like return lines? Im not talking about flex PVC though.

I am wondering what it is and how its used?

I have a 1" bulkhead in the bottom of my overflow for my return line. Inside the overflow is rigid PVC but from the pump to the bottom of the bulkhead I was hoping to use this tubing or "hose" as it would be easiest.

Just kind curious as to what it is and where to find it.