An electronic device (found in many, but not all power strips) that absorbs or shorts to ground the excess voltage from a voltage spike above a certain threshold. It is designed to protect the equipment plugged into it from potential damaged caused by the excess voltage. Transient Voltage Surge Suppressors, or TVSS's (the most common name for a surge protector) must be chosen carefully for the amount of excess energy (usually specified in Joules) that they can absorb before tripping their overcurrent protection device (usually a fuse), thus rendering them ineffective. Always select a TVSS that is Listed by an NRTL (UL or others), to avoid risk of fire. Note that almost no TVSS can protect equipment against a close-proximity lightning strike, despite the claims of some TVSS manufacturers.