The key difference between brass fittings and copper fittings lies in material:
①　Brass Fittings: Copper + zinc alloy, golden color, corrosion-resistant & cost-effective, ideal for plumbing & gas lines.
②　Copper Fittings: Pure copper (≥99.9%), reddish hue, superior thermal/electrical conductivity, perfect for high-end refrigeration & medical gas.
One-sentence summary: Brass is tough and practical; copper is pure and premium.

A PRV is your “pipe pressure bodyguard” — auto-drops city high pressure (130+ psi) to safe 50–80 psi, preventing bursts, leaks, appliance damage, and water waste. One line: High in, safe out — one valve protects everything. Best for: Homes, RVs, apartments, commercial.