What it does
Two-level pause condition. The base check pauses whenever the Mac is on battery power. With the threshold sub-toggle on, it only pauses when battery drops below the percentage you set.
How it works
Shake It On reads IOPSCopyPowerSourcesInfo for the current power-source type and capacity. The threshold mode compares the current capacity against your slider.
Where to find it
Settings → Paused When → On battery. Sub-toggle reveals a 5–95% slider.
When to use it
If you mostly use Shake It On at your desk: leave it on, threshold off. If you want it to keep going on battery while you have plenty of charge but stand down when you're running low: turn the threshold on, set it to 20–30%.