There's no such thing as "no pressure" when it comes to playing the trumpet. However, too much pressure is a familiar problem with most players at some point in their playing career.
To be used in conjunction with your Warburton trumpet top, the specially designed Optimal Pressure System (O.P.S.) fits right into your trumpet and works with your Warburton mouthpiece top to teach you to use less pressure while actually playing.
Just like a regular backbore, the special spring loaded chamber allows you to play nomally with a reasonable amount of pressure which can be adjusted. You can simply remove the 1 or 2 of the 3 internal rings and it will change the resistance to your pressure. Press too hard , and the spring compresses allowing air to escape, interrupting your buzz.