The string is made of the same material as the rope used when NASA's Mars Pathfinder landed on Mars. This innovative ligature incorporates a variety of ideas, such as the ability to change the tightness of the reed, as well as the sound and resonance, by moving the fine tuner bar. In February 2022, the "5th generation" was born, featuring a newly developed rocking bridge frame! Newly designed locking bridge: The bridge foot, which contacts the mouthpiece, has been improved from previous models, resulting in a more stable fit. This design also allows the bridge foot to function as a sounding board for the mouthpiece, amplifying the resonance of the mouthpiece and reed even more than previous models. ■CRYO4 Gold This is Silverstein's most popular classic model, characterized by its vibrant and bright sound. ■Applicable mouthpiece guidelines *Please refer to the size chart in images 6 and 7. *Please note that the size and fit may vary depending on the reed or mouthpiece used, the year of manufacture, etc., so please use this as a guide only. *Please contact us if you are unsure of the size. ■Specifications Dot code (5 laps) / 18K gold plating / Fine tuner bar x 4 / Ultra-low temperature (CRYO) treated / Includes omni-cap, hex wrench for size adjustment, spare locking bridge protection rubber, and outer box