AKA "Never-Out" or "Stay Lit"; A Polygroup proprietary “premium” light design that allows the string to stay lit even if a bulb is burnt out. Surebright can also be referred to as dual circuit technology.
2012 and older Surebright light strands have fuse bulbs that are glued to the base and CANNOT be replaced. (These can be identified by a white collar around the bulb for green base bulbs) Recommended fix is replacement of whole strand.
2013 and newer Surebright light strands have a gray base fuse bulb. These are removable and can be ordered and replaced by consumers.