Claude Gillard and Bill Molloy checking out the first Security Crossbow harness/container to arrive in Australia.

This tandem rig was manufactured by Security Parachutes in California USA.    It was the first of the harness/container systems to place the reserve parachute canopy on the jumper's back with the main canopy.    About a year later Pioneer Parachutes produced the "Para-Twin" that gave the choice of unzipping the reserve and mounting it on the back or front.   This model was popular with a few style jumpers that had perfected their style techniques wearing front mounted reserves but preferred the reserve out of their vision on accuracy jumps but it made no real impression on the sport market.   Pioneer also offered a side by side version of the piggyback but it never got off the ground.  

Like the ram-air canopy, the piggyback harness/container was accepted by both competition and fun jumpers very fast and these two pieces of equipment developed rapidly, bringing about an increase in performance, bulk, and weight reduction.   The need to manufacture rigs to re-equip the whole skydiving population of the western world also created a plethora of small manufacturers, many of which grew into large enterprises and gave the jumpers of today the fabulous range of equipment that there is to choose from when you buy a parachute rig.