I have the strip ruler. It does not slip which is wonderful. These are designed to use with the martelli rotary cutters which are ergonomic, left and right and require blades specific for this rotary cutter. I guess I am just used to a straight design on a rotary cutter rather than the maRtelli angle because the angle doesn't feel to be an improvement to me. Using the rotary cutter I prefer with the martelli strip ruler resulted in the ruler edge being "peeled" by the Olga cutter. Maybe I just don't know how to use these properly.