For a top-bound notebook that's flexible and will fit just about anywhere, try this one with super smooth Japanese paper. Each page has three solid lines dividing the page into two sections of micro-dotted lines, double-sided printing, and they're micro-perforated for clean removal.
Measures 2 5/16" wide x 4 1/2" 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.