MyVolts 9V power supply adaptor compatible with Sonic Research ST-300 Tuner - US plug This 9V high-quality power supply adapter serves as a replacement PSU for the Sonic Research ST-300 Tuner. The adaptor features overvoltage, overcurrent and short circuit protection to protect it from damage. Package Includes: - 9V US power supply; This is a fixed voltage 9V power supply adaptor designed to meet exactly the power specification of your device. Lifetime warranty - this power supply comes with a warranty covering up to the lifetime of your device, or 10 years - whichever is greater. Energy efficient - this power supply is Energy Star level 5 approved, guaranteeing more efficient delivery of power to your devices, at less cost to you.