Slim, easy to install and perfect controllability of contact through transparent housing material. What I am always annoyed as a hobby electrician with the old gray Wagoklemmen because I never really 100% could be sure whether the wire was really pushed all the way or not. Professionals have something natural in feel, or give the correct length already by precise stripping of cables against. The likely assemble them well 100s a month. I, however, only 6-12 per year. Therefore, it is easy to check by looking the right positioning of the inserted conductors for me an extreme benefit.
