Jerome Wiss instruments have a new system of pistons that removes 33% of the portals present on conventional pistons, which maintains a better tightness on the valve casing.

The Perinet pistons (conservitory system) that are used on almost all modern piston instruments have three curved tubes that the piston uses to make each connection, while the pistons developed by Jerome Weiss only have two curved tubes per piston. These curved tubes have a full bore, without any narrowing or mismatched bore sizes which are found on other brands. They are thicker than on other brands, allowing a longer life span, without increasing the weight of the piston or altering their velocity.

This new system also improves the feeling of the horn. This is becasue of the path taken by the air and the soundwave: on the instruments with Perinet system the air and the wave pass through a completely different tube, depending on whether the piston is pressed or not. On the instruments designed by Jérôme Wiss, the path taken by the air travels through the same tube half of the time whether the piston is pressed or not. The playing sensation is much more simular to a natural horn than with a traditional Perinet system.