For a top-bound notebook that you can tuck in a pocket, try this one with super smooth Japanese paper. Each page has a header area at the top for a title on the front (blank on the back) and they're micro-perforated for clean removal.
Measures 3" wide x 4.5" tall, 140 pages. Perforated white 80 gsm paper. Wire-o bound, black plastic front cover and thick chipboard back cover. Removable info sticker on the cover. Made in Japan.