For a top-bound notebook that's flexible for easily tuck in a pocket, try this one with super smooth Japanese paper. Each page has four solid lines dividing the page into three sections of micro-dotted lines, double-sided printing, and they're micro-perforated for clean removal.
Measures 3" wide x 5 1/8" tall, 100 pages. Perforated white 70 gsm paper. Wire-o bound, 5mm lines, black plastic front & back covers, rounded corners. Removable info sticker on the cover. Made in Japan.