Folks...Anyone know what size/name adaptor i need to be able to use on these female 6kg gas bottles? My van is fitted with a female pigtail tha goes to male fitting on 11kg gas cylinder..... so I want an adaptor that will fit my female pigtail and fit into a female cylinder as I have 2 full bottles from previous van I want to use up...I know I need a male to male but which size?...