The standard round flashing kit and 45 degree flashing fit can be used with the Outbacker Firebox or the Outbacker Portable Wood Burner as they both have a 60mm flue pipe.
Both flashing kits will clamp to your canvas, allow your flue pipe to pass through the canvas safely and prevent rainwater entering your tent.
The silicone on the standard kit will bend to the required angle and the 45 degree silicone is already set to that angle - it can just come down to which one you like the look of :)
For the Hygge Oval stove you will need the larger bell tent flashing kit.