I was searching for an A5 wire bound notebook with tear-out pages that would fit my Popov leather notebook cover. (https://www.wonderpens.ca/Popov_Leather_A5_Cover_English_Tan_Derby_p/pv-a5cet.htm)
Most spiral-bound A5 notebooks had the tearout portion A5 size - meaning that the overall size of the book was larger than A5. Not the Mnemosyne. The actual notebook is A5 (meaning the pages after getting torn out are slightly smaller) and the notebook fits beautifully in the cover.
The paper is lovely. Smooth and easy to move over. I've had no issues with feathering or bleeding. The line width is perfect for my favourite medium nibs. I really appreciate the date and title boxes as I often forget to date my notes until after filling the page. The boxes reminds me to do it up front and in a consistent format.
The micro perforation tears out easily (I first fold along the perforation) and leaves a clean edge.