Complex sentence: Some electric blankets work on a low voltage of 12 to 24 volts, including those which plug into ordinary household electrical outlets; in the US, such blankets are sold by Soft Heat, Serta, and Select Comfort.
Split into simpler sentences: Some electric blankets work on a low voltage of 12 to 24 volts. Such blankets include 16-to-24-volt blankets which plug into ordinary household electrical outlets; in the US, such blankets are sold by Soft Heat, Serta, and Select Comfort.