Crystal Guard. Headlight & Glass Protection GLÀZ® Crystal Guard™ is an advanced protective coating for glass and plastic headlights. It contains UVA and UVB absorbers that protect against daily sun exposure preventing premature yellowing, fading and cracking of headlights. Crystal Guard™ also extends the protection, long service life and beading effect of your existing glass coating or plastic coating. It leaves a crystal clear film that improves the clarity of headlights improving visibility on the road. Crystal clear finish Protects headlights against yellowing. Extends glass beading protection. By request/order.