Quartz sleeve for the Wallace & Tiernan WTL 3500 UV disinfection system, original part number AAC6256. It measures 540 mm long by 33 mm in diameter. A quartz sleeve is the transparent tube that separates the UV lamp from the water: the lamp runs dry inside it while the flow passes outside, and the quartz transmits the 254 nm germicidal output that ordinary glass would absorb. It is a wear part rather than a fitting — it fouls with scale and film, which cuts UV transmittance and therefore delivered dose long before anything looks wrong, and it becomes fragile with thermal and mechanical stress. Clean it on schedule and renew it when cleaning no longer restores transmittance, or when it is chipped, etched or cracked. Wallace & Tiernan is an Evoqua Water Technologies brand, and was part of Siemens Water Technologies before that, so the same equipment is catalogued under all three names and its parts carry Evoqua W3T/W2T and legacy AAC/AAD numbers. Item number 4103-0508. Original part number AAC6256. Supplied by cBallast on quote-to-invoice terms; lead time and freight are quoted per RFQ against the destination Incoterm.