Black Gold Pump & Supply is the proud inventor of the machine plunger. The machine plunger was designed for horizontal, deviated, and fluid pound conditions. Over the years, we have seen thousands of the top-open cages on the plunger assembly part due to the flex of the cage while pumping. This causes the threads to break off, resulting in a failure. In a regular plunger assembly, threads are exposed, which allows movement of the threads. In a horizontal, deviated, or fluid pounding well condition, the regular top-open cage may part. With Black Gold Pump & Supply's machine plunger, your cage will never part in the hole again. We machine down the threads on both the plunger and the top-open cage, which allows the plunger to be face-to-face with the cage creating perfect tension, and making it impossible for the threads to flex, bend, and part in the hole. We recommend this plunger in all deep, horizontal, and deviated well conditions.