51/400 Black Phenolic Royal Cap F217

The 51/400 designation should be verified dimensionally because nominal finish names do not guarantee identical sealing behavior. Likely development programs include prestige beauty, wellness, pharmaceutical, supplement, and specialty-product packaging. When the brief calls for a well-defined compression-molded closure, Part 136170, the 51/400 Black Phenolic Royal Cap F217, provides a practical specification to evaluate. Use filled-package trials to qualify fit, liner compression, leakage, and repeated opening performance.