I use these around my house for the down-spout (gutters). They are a hard but flexible hose. If you use this with the adapter (above), you could fabricate a pretty sturdy sewer hose. It's flexible, but very ridged. They also collapse (or snap) down or expand out. I've thought about using these for RV sewer hoses, but I've got a zillion feet of hose right now. Once it all springs pin-holes, I'm going to try this.
FYI, Home Depot and Lowes also sells this same stuff, that's where i got mime.
Lowe's, click here.