The thin 3700 is 1.38 inches deep against the standard box's 1.88. That sounds minor until you are stacking - two thins fit where one standard sits, which is how you get more organisation out of the same bag or drawer.

Right for flat contents: hooks, blades, leader material, small terminal tackle, or hardware. Wrong for anything with bulk.

Specifications
3700 size, thin depth (1.38 in)
Rustrictor rust-inhibiting protection
Dri-Loc waterproof seal
Adjustable dividers
Manufacturer part number: PLASE371