Generally refers to a compact fluorescent lamp containing of 4 U-shaped tubes, i.e. Quad Biax®, as opposed to Triple Biax® (4 tubes) and Double Biax® (2-tubes).
Quartz:
A name for fused silica or even melted sand from which many high-temperature containers are now fashioned in the lighting industry. Quartz looks like glass but could withstand the high temperatures needed to contain very high intensity arc discharges.
