The AquaCal AutoPilot union nut is designed for compatible plumbing applications where a serviceable union connection needs secure fastening. A union nut is useful because it helps clamp the union assembly together, supporting a stable connection while still allowing the joint to be taken apart for future service.This replacement is especially useful when the original nut is cracked, stripped, worn, or missing. Using the correct 2 inch union nut helps preserve intended fit and restores the dependable hold a serviceable plumbing connection needs.The 312-A is a practical hardware replacement for compatible AquaCal AutoPilot systems that need renewed union fastening and cleaner connection support. AquaCal AutoPilot union nut 2 inch size Helps secure compatible union-style plumbing connections Useful when the original nut is cracked or stripped Supports cleaner, more dependable connection retention