A Universal Check Valve is an optional accessory to use with your Hydrant Assist Kit (HAK). It allows you to service or remove your yard hydrant quickly without turning off the water. It therefore provides you the option to use your hydrant site for more than just a hydrant. For example, you can remove the hydrant and place a livestock waterer there. Another option is using the site for a hydrant (frost-proof) in the winter and then switching to a quick-fill pipe (providing full flow) to fill spray barrels in the summer. There is a Universal Check Valve to fit any HAK.