SteelSeries does sell replacement bands for $20/£20. However, the Pro Wireless (and the Arctis 7, which now uses the same band for the 2019 Edition) is slightly more durable, but I haven't had it long enough to know if it'll survive long-term usage.

After a few months, all the Arctis models we've tried have that problem. There's just one downside to the Arctis ski goggle band design: its tendency to slacken over time. It really does work in practice, offering the kind of fit that didn't feel as instantly snug and comfortable as the HyperX Cloud but stayed put in such a way that I forgot I was wearing a headset as the hours rolled by. The band's tension keeps the heavier aluminium headband suspended above your head. If you've owned an Arctis headset before, you're familiar with the Arctis Pro's basic design, which is available in black or white. Instead of a headband that sits on the top of your skull with cushioning to minimize discomfort, the contact point across the top of this headset and other Arctis models is a 'ski goggle' elasticated band. 10 hours per battery (2 batteries included)

Steelseries arctis pro