This part id is for one pair of Rolf 406mm (20") aero wheels with standard cassette. Internationally recognized Rolf Prima is handbuilding for us a very special, limited quantity 406 wheelset. This is the most aerodynamic wheel we offer, and about the lighest at 1250 grams. Rolf Prima's exclusive Paired Spoke Technology allows for lighter rims and fewer spokes, which yield considerably less wind drag, without compromising wheel stiffness, durability or stability. These wheels use 20 bladed Sapim spokes from Belgium. Each wheel is handbuilt right here in Eugene by a master technician. We do not recommend riders exceeding 220lbs to use these wheels. Add some flash and performance to your Bike Friday with this special wheelset. These are handbuilt to order, please allow 2 weeks for us to ship them.