This is a replacement or extra power adapter for your TVGuardian 401SD.
***Please check the back of your TVGuardian 401 SD to ensure it says 9VDC.***
This power adapter is for the TVGuardian 401SD. Please check the back of your TVGuardian 401SD where the power cord normally plugs in to see what voltage your device requires. This listing is for the 9VDC units.