Xray T3 progressive springs
Available for the T3, Xray’s new progressive springs marked 2.2–2.6 are soft at the beginning of the compression, similar to hardness 2.2, but become harder as the spring is compressed more in the middle, with hardness 2.6 at the end. Black color and laser engraved for easy identification. Available as a pair, the springs are individually measured, controlled, inspected and matched to provide identical damping characteristics. During the selection process, each spring is compressed in several fine increments and the values are recorded. Each spring is then matched with another spring of identical characteristics.
Source: Xray [teamxray.com]