These cast angles are to suit a 90 degree corner of your gutter. They are a one piece fixing corner. To install these you will require silicone and rivets.
Installation-Cut both sides of your gutter at a 45 degree angle. It is a good idea to leave a little bit of a lap on the bottom flat part of the gutter, lapping in the dirrection of the water flow. But making sure you leave a gap of about 10mm between the two sides of the curved section of the Quad gutter. Slide the cast angle into position from underneath. Then finish of with silicone and rivets.