The NiSi P-03 Gold Lens Pen is a great kit tool for keeping your glass as clean and clear as possible. The extendable fine-bristled brush on one end is used to remove solid debris from the glass without scratching the glass. After all of the solid particles are cleaned off, use the cleaning pad on the capped end of the pen to remove water droplets and oily residue from the glass to return your lenses and filters to their original crystal-clear state.