Adding fine black ribbed rubber matting to your sluice feeding area provides an instant recognition for the presence of gold. This let you know if you are processing good material without needing a sluice clean up.
As it can be replaced  it can extend the life of the sluice, as it protects the surface from impact damage caused by material being dropped on the feed area.
This is quality rubber mat as used in the manufacturing of the Caledonian range of sluices.