This 33 gram Inflatable PFD Cylinder allows you to replace a used cylinder in your inflatable Adult PFD. It is suitable for both Manual, and Auto/Manual inflatable PFDs and includes green indicator clips for both types. It can also replace cylinders that do not pass the yearly self-inspection test. This model is not for Childs PFDs. There is another product available with a 17 gram cylinder for childrens inflatable pfds.