The Elan E64 Field Book is a casebound, pocket-sized notebook that's perfect for land surveyors and engineers, but usable by anyone. It sports a waterproof hard cover (though not waterproof pages) and generally holds up well to abuse, plus its eye-catching shade of orange makes it easy to spot whenever you've set it down in a messy workspace.

For the purposes of surveying/leveling in particular, the left pages of this notebook feature a 6-column spreadsheet-style grid for tabulating things like backsight, intermediate sight, foresight, height of instrument, and so on. On the right, the pages are ruled in a tighter grid measured 8x4 to the inch. Additionally, there are 15 pages of curve tables and other practical info at the back.

If you're not a surveyor, you can still use this field book for things like keeping records of expenses/purchases/etc, making notes, drawing sketches, or whatever else you think a dual-grid notebook would be good for.

A single E64 book is $10 on Amazon. It's also available in packs of six ($60), twelve ($80), twenty-four ($145), and forty-eight ($240).