The last I knew the number of 1/2 frames identified through the research process were in the low 30's. As many know much changed within the PGCA and I do not know where that count is now if it was even shared or has been maintained. I did read on the PGCA BBS a while back the number low 50's but I do not know how reliable that was as I don't recall the source. I do know that the 1/2 Frame is the only Parker frame that was identified by size. It was marked on the interior surface under the top tang.