The RGZ-95 ReZEL (Defenser b-Unit) is the ReZEL equipped with the optional Defenser b-Unit backpack. Developed specifically for the ReZEL, the Defenser backpack is a space-use assault backpack for conducting rapid, preemptive attacks on the frontline or at enemy's stronghold. Due to the high skills needed to use the Defenser backpack properly, it is normally fitted on the ReZEL Commander Type, but there are cases of them being used by the normal ReZEL. There are two versions of the Defenser backpack, the 'a-Unit' and the 'b-Unit'. The Defenser b-Unit backpack is armed with mega beam launchers and mega particle cannons for concentrated single point attacks at mid to long range, and has additional generators to improve the operation efficiency of the suit's beam weapons. This backpack also has additional thrusters, and the usual side skirts of the ReZEL are replaced with movable, thruster equipped tail binders. In waverider mode, the tail binders boost the suit's propulsion capabilities, and in mobile suit mode, they improve the suit's mobility, allowing it to change direction quickly.
In the manga, when Full Frontal and MSN-06S Sinanju attacked the SCVA-76 Nahel Argama, some of the ReZEL pilots were given permission to use the Defenser units. Two RGZ-95C ReZEL Type C (Defenser a-Unit) were deployed, one piloted by Norm Basilicock, along with a ReZEL (Defenser B-Unit) piloted by Riddhe Marcenas, and a Stark Jegan to intercept the Sinanju.