This hangs on the side of a wire rack shelf. Our shelf height was 0.981 inches from the top of the top wire to the bottom of the bottom wire, so center-to-center was right at 0.8 inches. The smaller of these, #1, was able to hold a heavy school backpack, but flexed quite a bit. The thicker one flexed much less, though it isn't a replacement for a metal hook.

The thinner hook is 0.25 inches thick and 0.25 inches wide (from flat side to flat side). The inside radius of the hook end is 0.375 inches.

The thicker hook is 0.375 inches thick and 0.313 inches wide. The inside radius of the hook end is 0.5 inches.