Here in N.E. PA, It is still a myth almost that the Glock 21 SF is made with a standard single sided mag release button. I am going on my second year of searching for one and after trying several dozen shops I am going to find one or bust. I can not believe that these things are that hard to find even if a delear has to order from the factory and wait. I think our gun shops in this state kinda suck at finding stuff. Any fellow PA people out here know or have seen any sitting in a shop...? My desire is due to several failures of the G-21SF ambi mag release design during LE training. These were actuall personal expirences and since I know it happens and have had it happen to me my confidence in that ambi gizzmo is near nil.