Size
Select either 45 or 30 degrees. 45 degree is always advisable if possible as it provides greater weather protection. Select 30 degree only if space is an issue. For example, a 45 degree outlet may cause an unacceptable obstruction in a narrow passageway.
Connection
You can choose the method by which you would like to join the duct. Selecting 'Doby frame' will mean that the duct is supplied with a ready fixed frame on the end. These frames enable the duct to be joined by simply bolting it together - one M8 nut and bolt on each corner. Nuts and bolts are available in the Fixings & Supports section.
Selecting 'frame loose' will mean, as is suggested, that the frame will be supplied but not fixed to the duct. It can be fixed on with rivets or screws as part of the installation process. Situations where this may be useful are if the duct needs to be trimmed in length to fit a confined space, or where a duct needs to be pushed through a hole or gap and pre-fixed flanges would make this difficult.
Alternatively, selecting 'slip-joints' will mean the duct will be supplied with the ends fashioned in such a way that they slip one inside the other to a depth of 50mm. They can then be fixed with either drill-screws or rivets, and sealed with sealant or tape.
Selecting 'nothing' will mean the ends will be plain, as in the drawing on the product page.
Lastly, we can supply the outlets with a simple sheet metal flange that enables the outlet to be fixed directly to a wall if required.