The REACTOR 4, like all BR containers, is built using double wall construction. The outer layer is a tough 1000 pound Denier Cordura material and the inner layer is softer Parapak. This makes for a comfortable rig that will yield years of service and durability. The cutaway handle has been redesigned and moved to a position under the the right main lift web. This hides and protects the handle while still being easy to activate when needed. The shrivel flap has gone through a major re-design. Now using wider Velcro the rig's closing flaps also contain Nylatron stiffeners. This allows for better shrivel flap to container contact and adhesion. Another major re-design involves a new tuck flap on the leading edge of the shrivel flap. This is a very desired feature on BASE jumps where tracking occurs. The Tuck Flap protects the leading edge of the shrivel flap from the wind blast generated and also better protects the Flap prior to jumping. The harness of the REACTOR 4 has also undergone improvements.