It will be more fuel-efficient than comparable airliners and can carry between 210 and 330 passengers (depending on the design). It will also be the first major airliner to use composite material for most of its construction. This construction will include Alcoa Fastening System's (ASF) Ring Locked fitting series, a flareless, plug-in connector. This high-pressure titanium hydraulic adapter provides 49% weight savings over the previous plan, with each aircraft employing over 120 of these fasteners. The fitting has a 20° metal-to-metal seal and uses an elastomeric O-ring as a backup seal. "The design provides a leak-proof separable port-to-tube connection," accoring to AFS' Product Management Manager, Doug Pyle.