I had no idea that ProMag was making a cheap plastic knockoff (pictured above) of the J. Allen Enterprises, Inc. JAE-100 (pictured below) until I stumbled across it listed on the ProMag website (Midway has it for $269). I have never seen one in person and cannot judge on the (likely very significant) difference in quality and construction between this stock and the (much more expensive and incredibly well-engineered) JAE. The most interesting thing about it, visually, is the difference in grip design (as compared to the J. Allen Enterprises stock). JAE is located in California. With their market in mind, JAE designed their stock to be compliant with CA law. The JAE stock does not make the M1A into an “assault weapon” (according to CA law), whereas the ProMag stock will. In CA, this means you must fix the magazine when using the ProMag stock on an M1A.
JAE makes special note on their website that the stock is CA compliant:
As you can see in the photo below, we have designed the JAE-100 grip so that, when grasped normally, the web of the trigger hand would be placed well above the exposed portion of the trigger.