RANCILIO藍奇里奧咖啡機 SILVIA 蒸氣閥旋扭 

This knob does come with the spring.
It will fit the older version Silvia's, but there have been some reports that, depending on the position of the valve inside against the frame, as it is slightly wider, the knob shaft rubs up against the front panel. Some adjustment of the valve against the frame may be required.