Hart & Cooley UL-listed aluminum chimney liner systems come in 3 inch through 6 inch diameters, 25 foot and 35 foot lengths. The kit includes the components you will need to complete the project including: liner, cap, flashing, mortar sleeve, screws and installation instructions. These flexible liners may be used to line new or existing interior masonry or factory-built chimneys or vents. They permit a zero air space clearance (direct contact) between the liner and the chimney interior surface. The masonry chimney also may have a zero air space clearance to combustibles and the chimney exterior surface. Hart & Cooley aluminum liners may be used to vent listed Category I gas-fired appliances (not oil or wood) and other equipment listed for use with Type B gas vents.