One of the first things you should learn as a beginning cyclist is to ride with your elbows bent slightly so that you can maintain control in unexpected situations. Having sleeves that are designed to bend with the arms is a nice thing. Assos takes care to do this with their armWarmers.S7. They combine their traditional RX fabric from arm warmers of yore with their new RXQ. The result is a warmer that stretches well and bends easily. The RXQ material is lighter, but with its channeled structure, it traps air against your skin and maintains excellent warmth.
The two-panel design allows the seams to contour the arm better than single panel designs. You can see how it forms around the muscles. Because of the better fit, Assos only needs to put half a gripper, sewn to the RX half on the warmer around the bicep. The tailored fit does the rest of the work to hold them in place.
The Assos armWarmers.S7 come in three colors -- Black, Red, and White. There's a reflective tab on each upper arm. Sizes are 0, I, and II.