Compression springs are the most common spring configuration, and one of the most efficient energy storage devices. According to their applications, compression springs could be utilized in many shapes, including cylindrical shape, conical, barrel and hourglass. And the ends types of compression springs could be opened, closed ends, open &ground, and close, squared & ground. When you put a load on a compression spring, making it short, its coils push back against the load and tries to get back to its original length.