Knee pad rubber on fuel tank, left side, R50 - R69S ►see details

JG r50-R69S -L

The last batch of knee pads shows a shiny stripe down the center line.

Depending on the viewing angle, the stripe is more or less visible.

The knee pads may have a thin wax layer:

for rubber parts that are stored for a longer period of time, the wax layer ensures that they do not "oxidize" on the outside and remain neat.