desirable for the device 10 in certain circumstances such as if it is designed to be implanted within a patient 39 s body although the reservoir 14 and its central hole 35 are illustrated as having circular shapes they could have any other suitable rounded or angular shape such as oval square or rectangular additionally instead of being positioned concentrically with the longitudinal axis of the housing at the center of reservoir 14 as illustrated hole 35 could be offset to any desired nonconcentric location the reservoir 14 39 s pleated inner and outer sides 37 39 permit the volume of the reservoir 14 to be varied for example as seen in fig2 when the reservoir 14 is full then its pleated inner and outer sides 37 39 unfold a maximum amount thereby permitting the reservoir 14 39 s top 61 to be located a maximum distance from the bulkhead 15 39 s base 18 which forms the bottom of the reservoir 14 on the other hand when the reservoir 14 is empty or evacuated its pleated inner and outer sides 37 39 fold up a maximum amount thereby permitting the reservoir 14 39 s top 61 to be located a minimum distance from the bulkhead 15 39 s base 18 although the reservoir 14 is illustrated as having pleated inner and outer sides 37 39 the reservoir 14 may be any other suitable adjustable volume device.