Used when building your own mods, these connectors allow for an atomizer to be screwed in to them and connect to the power source.
Please note: This product is not used as an adapter to connect one battery to a different class of atomizer, it is used in a mod to connect the power source to. If you are unsure what this means then you probably want to look at the E-Cig Multi Adapters page as that will more likely be the product that you require.