When sourcing PTFE tube fittings, you must prioritize material purity and grade. Ensure the fittings are made from virgin PTFE for maximum chemical resistance. Key specifications include pressure ratings (typically up to 120 PSI depending on temperature), temperature tolerance (ranging from -70°C to +260°C), and connection types such as flare, compression, or NPT threaded. For high-purity industries like semiconductor or medical, verify that the fittings are manufactured in a Class 100 cleanroom to prevent contamination.