A relatively new alternative to surgery is the vacuum bell, also referred to as treatment by cup suction. It consists of a bowl shaped device which fits over the caved-in area; the air is then removed by the use of a hand pump.[41] The vacuum created by this lifts the sternum upwards, lessening the severity of the deformity.[42] It has been proposed as an alternative to surgery in less severe cases.[43] Once the defect visually disappears, two additional years of use of the vacuum bell is required to make what may be a permanent correction.[44][45] The treatment, in combination with physiotherapy exercises, has been judged by some as "a promising useful alternative" to surgery provided the thorax is flexible; the duration of treatment that is required has been found to be "directly linked to age, severity and the frequency of use".[46] Yet long-term results are still lacking.[43][46]