Hard-drawn copper tubing is hard and rigid. Either type M, L or K thickness. It comes in standard 20-foot lengths that are dehydrated, charged with nitrogen and sealed with rubber plugs at each end. It cannot be bent easily, so soldered or brazed fittings are used when making connections or changing directions.
This type of tubing is rigid, hard and stiff. It is not easily bent and should not be bent. Fittings are used to obtain the configuration needed for the installation. The length commonly available is 10 feet or 20 feet. There are three standard weight with different wall thickness for each type. Type K has the thickest wall tubing followed by Type L and Type M. If you need a higher pressure tube, thicker type is to be used to ensure it can handle the pressure of the refrigerant. Type L outer diameters typically starts from 3/8 inch followed by 1/2 inch, 5/8 inch, 3/4 inch, 7/8 inch, 11⁄8 inch, 13⁄8 inch, 15⁄8 inch, 21⁄8 inch and 25⁄8 inch.