Abstract: A multi-diameter bellows for use in a seal section of a submersible pump. The bellows is adapted to surround a shaft that communicates the motor with the pump. The bellows is made of a first collapsible section and a second collapsible section. The volume of the bellows is varied by moving a coupling member that attaches the first collapsible section to the second collapsible section. The coupling member has an outside portion for connecting to the second collapsible section and an inside portion for connecting to the first collapsible section. The coupling member additionally has a transitional section between the outside portion and the inside portion. The transitional portion of the coupling member allows the inside portion to be located within the second collapsible section, i.e., allows the collapsible sections to be “nested”, which increases displaced volume for a given stroke length of the coupling member.