just wanted to let fellow woodworkers know that spiral duct pipe and fittings are available locally at EAST COAST METAL DISTUBUTERS. they are located in raleigh on noblin rd. phone 919-872-3990. i purchased my duct pipe here and found there prices to be about half the price of AIR HANDLING SYSTEMS. the pipe they carry is lindab brand, this pipe has double gaskets and slides together easy, pulling it apart is another story! no clamps needed at joints, just a couple tek screws. good luck and i hope everyone finds this information usefull.