Fifteen inches sits at a genuinely useful scale. It is longer than a standard ruler by a quarter, roughly the...

13 inches sits in an interesting middle zone longer than a standard ruler, shorter than most laptop screens are wide....

14 inches sits in an interesting middle zone. It is longer than a standard ruler (which stops at 12 inches)...

20mm is about the width of a large adult thumbnail. It sits in a practical middle ground between too small...

19 mm sits in a genuinely useful middle ground. It is larger than a standard pencil eraser but smaller than...

18mm sits in an interesting middle ground. It is noticeably larger than something coin-thin, yet compact enough to fit inside...

Sixteen millimeters sits in an interesting middle ground. It is noticeably larger than a pencil’s width but small enough that...

15mm sits at an interesting crossroads. It is small enough to fit between your fingertip and thumbnail, yet large enough...

13mm sits in a genuinely interesting middle ground. It is larger than a centimeter but smaller than most people’s thumbnail...

Twelve millimeters sits in an interesting middle ground. It is too small to measure comfortably by eye, yet large enough...