When Shimano released its "deer head" rear derailleur back in the early 80's, it revolutionized the cycling world by effectively creating the world's first mountain bike drivetrain. Ever since then, Deore XT has come to be known as the benchmark for MTB groups. The front derailleur seen above is a prime example, providing crisp, smooth shifting performance at an incredible price. Designed for use with a triple crankset and 9-speed drivetrain, the FD-M770 seen above is a top-swing (low-clamp), dual pull model that fits a 34.9mm seat tube.
Everyone is shifting (ha!) to 1x11's right now and I just don't relate. The argument for a 1x11 is like the argument I hear people who don't ride bikes making for fixies. They say it's less complicated. It's easier to maintain. And since I carry up three flight of stairs to my loft, it makes it so much lighter. I think all of that is silly. I have used this derailleur for years without any more maintenance than a clean and lube every once in a while. I have never dropped a chain with it. And it always shifts crisply and beautifully. And while my friends with 1x11 systems are dealing with some sort of climbing or descending gear ratio compromise, I'm riding with my full 3x9 range.