Generally,the bathtub we see is the one fixed in the bathroom.There is another kinds of bathtub which is not fixed and can be moved. It is called Air-jet tub,or air bath tubs, are an increasingly popular alternative to water jet/Jacuzzi style tubs.
Although the freestanding tub looks like a soaker model, its cast-acrylic double-wall design contains dozens of strategically placed air jets. Use an electronic keypad to adjust air flow from gentle to vigorous or to pulsating massage. For more pampering, an aromatherapy setting diffuses essential oils.Air jet tubs provide a relaxing massage of thousands of bubbles of heated air released from tiny air jet holes arranged along the tub's bottom. Like most water-jetted tubs, air jet tubs include electronic controls to provide varying speeds and massage patterns.