Found a source for the Silica Gel to use in the rear of the Headlights, to stop them misting up.
The people who make Double Glazing Units, use it to stop their windows misting up !!.
It is placed into the window surrounds before the units are sealed up.
I asked if I could have a small quantity - - yes !.
The Gel is small brown round pellets, look like Seeds.
Got some in my Headlight now on TEST !!.