There are several models in this category. The biggest difference in operation is in the way you operate the pumps. For example, there are models that you use by means of a hand pump and there are models that have an automatic pump . The models that you operate with a hand pump are designed in such a way that you can easily release air thanks to a vent valve . Most hand pumps also have a pressure gauge , so you can measure how hard you are pumping. Automatic pump The automatic pump is a pump that works on batteries. This allows you to enjoy the pump hands-free . You also have the advantage of vibrations that can provide a pleasant feeling.