i think glock is waiting for results from the sales of its glock 17/22/19/23 line which are its best sellers and all come are offered witing gen 4. if they sell well, they will probably offer the glock 21 line with that option. I believe that the glock 21 came with the rtf2 option very briefly, but it was discontinued when most folks deemed the rtf to be a too aggressive of a grip for your everyday shooter