This may just be folk lore but my understanding of the history behind the STA is as follows:
As indicated in other responses, early back plates and wings did not have cam strap slots cut into them as they were orginally designed to support a double tank setup. Lamar Hires' (owner of Dive Rite) wife wanted to try using a plate but wanted to dive with a single tank. Lamar took a backplate and cut out the center section, flipped it over and bolted it to another back plate while sandwhiching a pair of cam straps between the plate/wing and the cut out center section, and thus the STA was born.
Fast forward a few years and slots began being milled into plates and designed into wings for camstraps specifically so they could be used for single tank diving, but divers being a bunch frugal b@st@rds did not want to own 2 plates, one for single tank diving, and another for doubles, and threading cam straps in and out of plates and wings proved to be cumbersome, so that cut out center section found its use as means to quickly and easily convert a BP/W setup between single and doubles configuration.
It was never meant to be "roll control" for single tank bp/w setup....the fact that it offers that is a bonus, but at the cost of moving the tank further away from the diver's back.
Some of us swear that it is necessary for single tank setup. Some of us find we don't need it. Some of swear that some form of "roll control" is absolutely necessary, and some of us have never had a problem without any.
-Z
As indicated in other responses, early back plates and wings did not have cam strap slots cut into them as they were orginally designed to support a double tank setup. Lamar Hires' (owner of Dive Rite) wife wanted to try using a plate but wanted to dive with a single tank. Lamar took a backplate and cut out the center section, flipped it over and bolted it to another back plate while sandwhiching a pair of cam straps between the plate/wing and the cut out center section, and thus the STA was born.
Fast forward a few years and slots began being milled into plates and designed into wings for camstraps specifically so they could be used for single tank diving, but divers being a bunch frugal b@st@rds did not want to own 2 plates, one for single tank diving, and another for doubles, and threading cam straps in and out of plates and wings proved to be cumbersome, so that cut out center section found its use as means to quickly and easily convert a BP/W setup between single and doubles configuration.
It was never meant to be "roll control" for single tank bp/w setup....the fact that it offers that is a bonus, but at the cost of moving the tank further away from the diver's back.
Some of us swear that it is necessary for single tank setup. Some of us find we don't need it. Some of swear that some form of "roll control" is absolutely necessary, and some of us have never had a problem without any.
-Z
it just feels right, intuitive, nice fitting. I guess the more backwards-drifted air distribution in the bladder helps for my heavy hips/legs.
