The springs are excellent for my industrial and scientific projects. My analysis of these springs showed that they can be compressed to an extended diameter which makes them perfect for heavy-duty use. They are made of stainless steel, so they wont rust or corrode over time. One downside is that they are a bit pricey compared to other options on the market .But overall, I'm very satisfied with my purchase and would recommend these springs to anyone in need of reliable and sturdy power transmission products..