Streamlight Head O-Ring for Scorpion/PolyStinger LED/DS LED Flashlights 850017 replaces the front waterproofing ring inside the front outer casing of your Streamlight Scorpion and Polystinger Flashlight. In order to replace the front face housing o-ring of a Scorpion or PolyStinger lantern, this Streamlight O-Ring is the part you need.