The Riser Cap is designed to provide a means of sealing the opening at the top of the fill and tank probe risers from unwanted entry of the elements (e.g. rain water, dirt and dust, etc.) into the UST.
They are attached directly to the top of the riser pipe, and are locked into a sealed position by pushing down on the handle. They can be quickly removed simply by lifting the grasp handle on top of the cap.
Some types of caps come with a locking mechanism which will not allow the cap to be removed from the riser without the use of a locking key and key code. Riser caps are typically constructed from aluminum and/or stainless steel, and they must be compatible with the product stored in the tank.