| 摘要 |
A unitary metal vent apparatus for securement to the roof of a building is formed from a single aluminum disk, into the form of a first flange portion, a tubular second portion, a cap-shaped third portion, and a vent hole portion disposed between the tubular portion and the cap portion. Preferably, the apparatus is produced by spinning a tubular protrusion in an aluminum disk, drilling vent holes, and collapsing the end of the tubular protrusion to form a cap-shaped portion. |
