Phase 1: light pressure, the stainless steel roller absorbs this. The elastomer is only lightly compressed
Phase 2: a medium load, roller and bumper are simultaneously compressed
Phase 3: fully loaded, maximum pressure. Roller as a limit stop prevents excessive compression of the elastomer thus resulting in a longer service life.
The stainless steel roller rolls during decompression.
By the way, the roll bumper by Kiesling is available only in red colour -the externally visible sign for the pure materia of the elastomer whereas a standard bumper contains soot particles and is therefore black.