Firm Gas Sales Service (FS-1) [PDF - 80 KB] - MGE provides company-owned natural gas supply on a firm (not interrupted) basis. Choose this gas supply option for the entire service (full requirements) delivered under GSD-1 distribution service or for a nominated (selected) amount of daily service taken along with either IS-1 or DBS-1 service. The cost of gas under this service changes from month to month.