Abstract: Disclosed is a kit of low cost, light weight, corrosion resistant components, including a plurality of extruded members, certain ones of which components are factory preassembled into climbable and unclimbable tower units selected one of which are adapted to be rigidly connected end-to-end by overlapping couplings into a tower at an installation site to support a power line or other load. The couplings and the overlapping surfaces of the tower units have teeth that mesh to lock the couplings in place. The tower is specially suitable for erection in confined areas to heights in excess of one hundred feet to support power conductors. A number of components are selectively attachable to the tower in a wide variety of ways to support high tension insulators in suspension and/or cantilever fashion and to anchor guy cabling to the tower.