| Product Type: | Condensation Drain |
|---|---|
| Installation Type: | Vertical |
| Diameter (Inches): | 3" |
| Application: | Plumbing |
| Vent Type: | Single Wall |

You would get the same size ducting that unit installation calls for. If you have the model number of the unit you are referring to we can cross reference and see which diameter you need.
Yes. Z vent is category 3 stainless steel.
The rough in length is 5.75".