Copper Plumbing Tube with outside diameter always 18" larger than the standard size. Each type (K, L, M and DWV) represents a series of sizes with different wall thickness. The inside diameter depends on tube size and wall-thicknesses.All four types are available in drawn temper straight lengths 20 feet long. Type K, L and M are available also in annealed temper in 8 feet straight lengths or in long coils in sizes from 14 inch to 78 inch.