This adapter can be used to adapt any of the current 3-bolt fuel cell filler necks currently used by the FCST-X onto a legacy FCST that uses a 6-bolt hole pattern fuel filler. The adapter adds less than 1/2 inch of height to the filler cap or neck when installed. To include the same safety measures as the previous models, rollover protection is built-in using the same one-way valve that legacy FCST fillers used. A new gasket is also included. COMPATIBLE FILLERS This adapter is compatible with 3 filler options which can be selected in the options on this page. It will also be compatible with all FCST refueling kits found HERE. 20-1197-V Direct Mount Fill Neck & Cap Direct filler cap with vent and rollover valve built-in. 20-1027 Straight 1.5in Barb Filler Neck Filler neck with a 1.5" straight barb for connecting a filler hose that routes to an external/remote fuel filling point 20-1047 Remote Mount Fill Neck 24AN Elbow Filler neck with a 24AN connection and a 1.5" barb on a 75° angle for connecting a filler hose that routes to an external/remote fuel filling point. This filler neck's elbow can be clocked to point any direction needed.