I can honestly tell you from personal use these things are the best. The fit in your back pocket perfectly without being too bulky so you can carry them everywhere you go for drawing, taking notes, revisiting, etc. Don't look like you're texting someone during a meeting when you're actually taking notes. Put the damn phone away and put real pen to real paper. It's just good for the soul.
The original Field Notes 48-page memo books, available in a nice 3-Pack. Each book measures 3-1/2” wide by 5-1/2” tall and is bound with a rugged three-staple saddle-stitch process.