Abstract: An inflatable packer comprising an elastomeric tubular core, an outer cover, an annular reinforcement sheath sandwiched between the core and cover comprising a strength zone composed of strain-resisting elements of high modulus extending helically at alternate lay angles of less than 40.degree. with respect to the packer axis, and sleeve means to which the reinforcement is securely attached at each end of the packer. In one embodiment a transition reinforcement zone is interposed between the tubular core and strength zone to improve the flex properties and increase the life of the packer. In another embodiment an improved anchor means formed of a frusto-conical matrix encapsulates embedded reinforcement members.