Black polymer is the most common filtering material for observing sunspots and granulation, through telescopes and binoculars.
Make a filter on your own for any telescope / binoculars / camera, and for a fraction of what factory made filters cost.
The sun will appear in a natural orange color when viewed through your telescope using this filter.
WARNING: ALWAYS MAKE SURE THE FILTER IS WELL ATTACHED TO THE TELESCOPE/BINOCULARS, USING STICKY TAPE, TO KEEP IT FROM FALLING WHILE OBSERVING!