It's called "good vibrations", a hard foam tube, $3.00.
In the lawnmower section, comes in black, red, and green.
It's 1' long, I cut mine in half.
It comes pre-slit, with removable contact paper glue stripes on the inside.
It doesn't quite completely wrap a 1 1/8" top tube, but it looks like it does, and it's enough to protect.