I love these boxes. Excellent value for money and quality. The boxes that come with it are a bit more expensive, but they're worth it. There are 2 box sizes which was confusing for a while - with all the sizes it took me a while to figure out there are only 2 options, large and medium - 3inch and 2inch. The dimensions are the same for all 3" and 2" models. Also, I didn't know there were 2 versions of drawers: a sturdy one with rails, which is expensive, and a cheaper one (for 3" and 2" respectively). Then simply select the number of boxes. I have a cheaper one, it's very good but sags a bit due to the weight I put on it. If I did it again, I could get expensive. It will probably go on for the rest of my life (buy once, cry once). Still, I probably have at least a hundred pounds (maybe more? maybe less?) - at least 6 boxes of a stack. Filled to the brim with screws, nuts and bolts. Works perfectly. I like the box itself, and certainly that's what it's for. I thought I really need a 3 inch. And I have 4 of them, but actually I prefer the smaller ones. Obviously what you store makes a big difference, but I've found this particular box to be ideal for most nuts and bolts. I have 2 stacks of boxes labeled M5 - M14 (screw size, M4 and smaller in a smaller container) and 6-32-10-32. At 1/4"-20 and up, I opted for a 3" box. And a few more boxes for other stuff, washers, plastic spacers etc. The smaller box size is ideal and I could make another one with an even larger one. 1. Number of smaller compartments. Again depends on your needs - I've hot glued dividers with smaller screws. I want the latch to be stronger so I have more confidence that if I drop it I have more confidence that I won't spend the next 8 hours sorting screws. So there are options for smaller compartments, but that's me. There is one adjustable compartment, but it's surprisingly difficult to find additional dividers for drawers (both 2" and 3").