8-1/2" replacement lens gasket for the Pentair Amerlite and SAM lights.  Replaces the OEM lens gasket 79101600.
 
The lens gasket provides a seal between the face ring and glass lens to prevent water from getting inside the fixture.
 
It is strongly recommended to replace the lens gasket when replacing a pool light bulb.  Over time, use, heat, and chemicals will compress the gasket and can cause it to fail, allowing moisture to damage the light.  A light bulb change is the perfect opportunity to replace this very important seal.