This page is dedicated to trying to explain the different materials, feeling them is the best way, but I found a few ways that I could display the way they compress and bend.

First up is the compression test, The example pieces are Spear B (15mm) Solid (No Bore Hole), #18, #10, #0050, and #0020. The piece is laid on a flat table, a steel plate is placed on it to distribute the weight, a rubber spacer is added to make room for measuring easier, then a 5lbs weight is added. I measured the distance between the bottom plate of metal and the table, the number refers to the millimeters of distance that was lost during the loading of weight, recorded and then another weight was added, then
again and again, for all four firmnesses.

In this test I have the pieces laying on a ream of paper, with the tip drooping off, there are also a few stainless steel rods holding the pieces to the paper so they cant buckle up. you can see that the softer materials flop down more than the more ridged firm pieces.