Type L copper: medium wall thickness. ASTM B88. Sizes: 1/2 in (0.040 wall), 3/4 in (0.045), 1 in (0.050), 1-1/2 in (0.060), 2 in (0.070). Working pressure: 1/2 in = 1,137 psi at 100°F, reduces at higher temps. Joining: soldered (lead-free per Safe Drinking Water Act), brazed, or ProPress mechanical. Maximum service temp: 400°F. For underground: Type K (heavier wall). Type M (lighter) for drain/vent only. Cost: $3-$8/ft for 3/4 in. Advantages: corrosion resistant, antimicrobial, long lifespan (50+ years), recyclable. Disadvantages: expensive vs PEX, theft risk, pinhole leaks in aggressive water, expansion noise. CSI 22 11 16. Derating for hot water: 150 psi at 250°F.