A prosthetic cushion liner and cushion locking liner for use as a standalone interface between an amputee's residual limb and the interior of a prosthetic socket. The liners include a fabric covering having an open end for introduction of a residual limb and a closed end opposite said open end, and a cushioning block copolymer and plasticizing oil gel composition residing on only an interior surface of the fabric covering. The gel composition includes some amount of a Septon J-Series thermoplastic elastomer material, and/or some amount of a Septon V-Series thermoplastic elastomer material, and/or some amount of a Septon Q-Series thermoplastic elastomer material. The cushion locking liner further includes a distally-located connecting element for coupling the liner to the socket of a prosthesis.