Briggs & Stratton part 694395 is a genuine OEM carburetor primer bulb designed for small gasoline engines. Its primary function is to draw fuel into the carburetor to assist with easier starting, especially after the engine has been sitting for a long period. Product Details Part Type: Carburetor Primer Bulb Primary Function: Primes the carburetor for faster cold starts. Design Feature: Typically features a small hole in the center which is intentional for proper suction and pressure release.