Stay hydrated with the patented Speedfil F2 system. The F2 works with any Specialized thread compatible water bottle in both 21 fl oz. (621 ml) and 24 fl oz. (710 ml) sizes. The F2 model enjoys many of the same benefits as our Speedfil F1 system but the F2 works with any standard cage mounted on the down tube. The dual splash resistant design allows the rider to refill the system on the fly. Only prime the Speedfil system once and you have access to your hydration immediately. The bite valve keeps fluid on demand without sucking up air after each drink. The F2 can be used by triathletes, mountain bikers, as well as recreational riders. For a complete hands-free solution Speedfil recommends combining the F2 system with our exclusive Speedfil Micro-Retractor (sold separately or included in the Off-Road Bundle). This retractor allows the rider to pull the drink tube up to 24 in. (61 cm) from the handlebars, drink, and then release. The retractor snaps back inside the keeper.