I recently purchased a new soft cover 13x21cm mole and a mole pen that is designed to attach to the notebook. The pen is flat and has a side clip that is supposed to be designed to attach to a hard cover mole. I noticed that the pen would have to be attached to the outside of the mole which would not be a very tidy or secure package. I realized that if there was a slot cut into the pages of the mole with just enough space to fit the pen, then the pen could be attached to the mole hidden within the cover. Only a small amount of page space would have to be removed, which I deemed worth the tidy package that would result.