The camming surface 32 while in the embodiment comprises a centre rib. The centre rib also provides added strength for the channel. In some installations the louvre assembly is screwed in to the window frame throughout the centre of the channel. It's also identified to have end clips configured to https://wardrobe-hinges50358.blogprodesign.com/35009053/5-simple-statements-about-pivot-hinges-for-exterior-doors-explained