That is a Pentair Replacement Light Pilot Screw with Captive Gum Washer. Used with various Pentair pool lights such as the Amerquartz.
Pilot screw replacement
Fits Pentair IntelliBrite 5g Color and White LED pool lights
Also fits Pentair SAm Spectrum Amerlite, SAL Spectrum Aqualight, Amerlite and AmerQuartz pool/spa lights
Also compatible with Pentair Sta-Rite Sunbrite II and Sunglow II pool/spa lights
Made of stainless steel and includes captive gum washer; Measures 4-inch length by-inch height by 3-inch width
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