I bought a set at Paducah a few years ago--it has the 2.5, 4.5 and 6.5 half square triangles and I love them. I also bought the flying geest (finished 3x6) and use it a lot. I have the 9.5 half square triangle ordered now for a quilt I want to do. I love that they hold and don't slip. I am doing a class at my local extension office and tried to show the half square triangle to the instructor and she didn't even want to consider it. She told everyone there was no need for specialty rulers when the ones you had have the 45 degree angle on it (sure they do, and they can slip very easily too!). The ruler got passed away anyway and I noticed quite a few people were writing down the website for BlocLoc. I know they aren't cheap but I am a gadget person and love tools that make things easier to do and very accurate!