Problem #1: Cheap plastic is very flexible so can't stay flat. Problem #2: Instead of a little bunny on the edge to avoid mistakes when painting, there are two raised paths running down the middle of the ruler, keeping it out of the way. It is not very stable and allows the ruler to swing back and forth easily. Some of the triangles I draw slip right under the ruler if I'm not careful. Problem #3: The same guides in the middle hold the T-head above the drawing board, causing the drawing triangles to get stuck on it and not be able to slide over the edge of the drawing board. Who designs this crap? I recommend Minerva or Graphoplex. They are made of high quality acrylic. They're not widely available in the US, but you can order them from Revain's UK site.
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