a sterile medical liquid container system that includes an inner cap and an outer cap nested together and having interconnecting splines . the inner cap has internal right - handed threads and is screwed onto a threaded bottle neck to hermetically seal this neck . the outer cap has external left - handed threads and is fused at a frangible joint to the thermoplastic bottle . a jacking ring with internal left - handed threads screws onto the outer cap and a continuous clockwise motion of the jacking ring acts to fracture the outer cap , and unscrew the combined intersplined inner and outer caps from the container neck .