The quartz sleeve holder — the quartz glass nut — for Trojan A-series reactors, original part number 793074. It is the threaded gland that clamps the quartz sleeve into the end chamber and holds it concentric against the sealing face. Because it sets the compression on the sleeve seal, it is a part that matters more than its price suggests: overtightened it stresses the glass, undertightened it lets the sleeve weep, and a nut whose thread or sealing face has been damaged will do one or the other whatever torque is applied to it. Inspect it whenever a sleeve is changed and replace it if the thread is galled or the face is scored. Supplied by cBallast on quote-to-invoice terms; lead time and freight are quoted per RFQ against the destination Incoterm.