The shoulders and elbow area is covered with an additional layer of fabric called SuperFabric which is very grippy and abrasion resistant. When you put a pack on it stays put on the grippy SuperFabric shoulder patches, and does not move around. With most jackets the slippery nylon allows the pack to slide all over you shoulders and can be annoying while motoring down a trail.
Over the long run, the additional protection in the elbow area will help the longevity of the jacket and protect it the event of a crash, which all of us are prone to do on an occasion. The arms of the jacket are cut fairly wide, so I could wear my elbow pads under the jacket.
The jacket has some very interesting additional features, one of which is the drop down tail. It is really a butt drip protector. As water dribbles down your back when it is raining, the flap lets the water roll off past your saddle, keeping your derriere drier. That is a great cycling specific innovation!
The flap sits up inside the jacket, and is held there by 2 buttons. With a bit of effort it is easy to reach back and pull the flap down while riding, so when it starts to pour you get that extra amount of protection.