I have a G-21SF w/M1913 rail, and I'm wondering if it's going to be a rare item? I bought it for the rail and the SF feature and ambi. mag release. Which I feel the M1913 rail is a great idea, and I would really wish Glock would build a G-17 with this rail system, I would go without a ambi. mag release. I really enjoy my G-21, though, I feel there won't be much of a market, like other Glock's with different marking's. They'll just hold there value.