How long will the “RT-96” Cool Cube™ last? L How long will the “RT-96” Cool Cube™ last? The RT-28 when properly conditioned will hold product between 20-24°C for 56+ hours. Post navigationPrevious post: How long does it take to get the “BT-96” Cool Cube™ ready to hold my vaccine?Next post: How do I prep the “RT-96” for use?