Concept HID Bulbs use ultra high quality 100% Quartz glass to construct the main bulb component. The glass houses an OEM-grade xenon capsule using high-quality halide salts from our materials supplier. Our bulbs use an OEM-inspired mounting and alignment system to keep the bulb perfectly centered where it needs to be – this is probably the most important aspect of why Concept Series HID Bulbs are the best of the best.