These are not winglets. Winglets are fixed. These are new longer wings, which would make the aircraft too wide to use existing terminals, except that Boeing ha

These are not winglets. Winglets are fixed. These are new longer wings, which would make the aircraft too wide to use existing terminals, except that Boeing have built the wingtips to fold up while taxying and at the gate. In flight they are extended straight out as extensions of the wings. Winglets are cool, but a longer, straight wing can achieve the same effect more efficiently by giving the wingtips washout (negative angle of attack).