The answer is it depends. SX bullets made 2024 vs pre-2024. (See note below)
I am currently using pre-2024 SX active black bullets with my Element Copper power cord. The original versions of the active gray and black bullets have a smooth cylinder. Later versions have a partial ribbing on the cylinder. Gray bullets are no longer made. They now have red, blue, gold and silver. Also, a more expensive Master Series.
SR makes both active and passive tuning bullets. Each has a different connector. Later model SR cables may use one or both - depending on the model. The upper tiers use both.
It’s best to call Synergistic Research directly, They have excellent customer support.
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* It looks as if there is an older SX series and a newer SX series. The older SX active bullets are compatible with the Element Series of cabling. The newer SX active bullets with this new design are not compatible.