Through our partnership with the Australian Institute of Sport and rigorous product testing we have developed a Support Factor (SF) rating system for sports bras to help women choose the right bra for their needs. Only BERLEI sports bras have been tested, used and approved by the Australian Institute of Sport. Support factor 4 bras are ideal for extreme impact activities such as long-distance running, kick-boxing and athletics. SF4 sports bras can reduce breast bounce by up to 60%. Only BERLEI sports bras have been tested, used and approved by the AIS (Australian Institute of Sport).