Introduction of the rocket pack to the range of Mk. 4 and Mk. 5 seats created the basic Mk. 6 and Mk. 7 ranges respectively. However, many of the Mk. 7 range of seats were subsequently embodied with additional improvements in design such as Power Retraction Systems, Remote Fired Rocket Systems and Sequencing Systems as later described. Following development of the highly successful Mk 10 rocket assisted seat, a simplified, lightweight variant of this seat, designated the Mk 8, was introduced for primary trainer aircraft, such as the Embraer Tucano. The most significant design simplification was the removal of the rocket motor, to save weight. In most other respects the Mk 8 seat retains the excellent design features and functionality of the Mk 10 seat. The Mk 8 seat provides runway level escape at speeds down to 70 knots, and has a maximum escape speed capability of 425 knots.