A variable length endovascular prosthesis adapted to prevent endoleaks is provided that includes a substantially tubular first graft member having an interior surface, an exterior surface, and a proximal end, and a substantially tubular second graft member slidably engaged coaxially within the first graft member. The prosthesis further includes a substantially tubular fluid-tight connecting member attached at one end to the first graft member and attached at another end to the second graft member. The connecting member is axially compressible and expandable to facilitate engagement of the second graft member within the first graft member while maintaining a seal between the graft members.