The DuraTech 8 Class A Chimney Pipe Round Ceiling Support Box The round ceiling support box is used to support chimney pipe and provides a positive connection between support box and chimney with a built-in twist-lock. Supports up to 60' of DuraTech Chimney. Use adapter to attach DVL or DuraBlack to the support box. Painted black. Trim collars are sold separately.Trim Collars Sold Separately Built-In Twist-Lock Supports Up to 60' of DuraTech ChimneyFuel Type: Coal, Gas, Oil, Wood Material: Galvanized Steel Pipe Class: Class A Pipe Inside Diameter: 8 Pipe Shape: Round Style: Functional UL Listed: Yes Vent Construction: Double Wall Weight: 4.3