The Astrojax Spectra line is for jaxers ages roughly 7 to 77 (or 78 ... or maybe 79). The low-friction, longer (40 inch) string and heavier (roughly 26 grams) balls provides smooth, easily controllable orbits.
The balls are about the same weight as those of the (discontinued) Aqua version of Astrojax. The string has a custom-made coreless weave which provides extra stretchiness and low sliding friction, which is why Spectra orbits (particularly at the bottom of vertical orbits) feel so smooth. End stoppers are created by knots around black o-rings.