Jetstream has been around for decades and been updated in three major steps. The model with number 2960 was the first, 3960 second and the current model namned Mk3 consists of the same servo-assisted second stage with the Xstream first stage. The combination makes for an easy to breathe regulator with massive airflow that is extremely durable and trustworthy. For this reason, the Jetstream has been used by the US and Swedish navies as well as the Italian Police.