The Castelli Free Aero Race 4 Bib Shorts draw on 12 years of aero bib short evolution to deliver ride perfection. The Free Aero Race 4 Bib Shorts feature some dramatic, performance-enhancing changes. Dimpling on the legs stops air attaching to the fabric so that air comes off cleanly and allows for better print quality too. The leg gripper features a lie-flat raw-cut edge with vertical silicone stripes to keep it in place without restricting stretch and leg movement. The bib shorts\' panelling has improved fit for support while making the shorts look even cleaner. Castelli has re-engineered the bib straps with a lighter, more breathable material so they stay cooler, lie flatter and are more durable. A new loop for race radio microphone was added at the request of team riders. The Bib Shorts use Castelli\'s Progetto X2 Air Seamless seat pad. The pro-level seat pad consists of two separate layers: a soft stretchy layer that sits next to your skin and prevents any rubbing, and a perforated cushioning layer with two separate density foams along with breathable perforated gel inserts. Key Features Vortex dimpled fabric on legs for aero performance Forza fabric on inner legs with 38% Lycra content for the perfect fit Stripe mesh engineered minimalist bib construction keeps you cool Giro4 leg gripper elastic for better grip distributed over a larger area Doppio V construction in front for increased support and comfort Flat-lock stitching Progetto X2 Air Seamless seat pad 15-35C / 59-95F Weight: 172g