Abstract: A top cap assembly for use with tube cap assemblies in sealing access points in irrigation systems. In one implementation, a top cap is coupled to a locator component to remotely locate the tube cap assembly. The locator component includes a metallic portion, an audible response mechanism, or other device that provides indicia usable to locate the tube cap assembly. In another implementation, the top cap includes an advertisement portion configured to removably receive indicia. The advertisement portion includes a grooved insert which receives a business card or advertising label. In another implementation, the top cap and/or base collar include grooves which receive an O-ring, and a portion of the tube cap assembly compresses against the O-ring to create a watertight seal. In still another implementation, a method to identify one or more indicium of a top cap is provided according to the present invention.