Fiber Stream originally had a body contoured cosmetic "bumper" and a short tube up front to store the sewer hose.
When I bought mine, the bumper had been replaced with a wood 2" x 4".
I liked the idea of a 4" x 4" hollow bumper to hold the hose; I didn't want a rusty metal one.
Mine is a vinyl fencepost sleeve from Lowe's. It bolts to the brackets on the frame that held the original bumper.
The rubber endcap "expands" to fit when you press it from convex to concave. I haven't lost it yet.