When sourcing for Plasma Enhanced Chemical Vapor Deposition (PECVD) processes, the purity of the quartz is paramount; look for SiO2 content ≥ 99.99% to prevent metallic contamination of wafers. Dimensional precision is critical, specifically outer diameter (OD) and wall thickness tolerances within ±0.5mm to ensure a vacuum-tight seal with flanges. Additionally, verify the hydroxyl (OH) content, as low OH levels (typically <5 ppm) are necessary for high-temperature stability and to prevent tube sagging during long deposition cycles.