Which copper tubing type is thinner than Type K and is blue?

• A. Type K
• B. Type M
• C. Type L
• D. Soft & Rigid

Answer: (C)

Copper tube types differ in wall thickness, which affects strength and pressure capacity. Type K has the thickest wall, making it very robust. Type L sits between K and M in thickness and is coded blue, while Type M is thinner and often coded red. The question asks for the tube that is thinner than Type K and is blue, which is Type L. This makes Type L a common, balanced choice for many residential plumbing needs, offering a good mix of strength and flexibility. The blue color helps distinguish it from the other types (Type K is green; Type M is red). The “Soft & Rigid” designation refers to the tube’s temper, not its thickness or color, so it isn’t the blue, thinner option.