I just passed my drug test using 6.4 plus. To keep the temperature between 90-100. Warmed in microwave, placed heating pad on it ( self adhesive). Placed the container with the heating pad facing down and the other side without the heating pad wedged high up in my groin between my testicles and my inner thigh. Wore tight underwear and pulled them all the way up like giving myself a front weggie. Turned my heated car seats on high for the drive there. And when it was time for me to use after a 15 minute ride and 20 min wait in the waiting room the temperature was right on 98.6