This modules macthes IP sets which can be defined by ipset(8).

--set setname flag[,flag...]
    where flags are src and/or dst and there can be no more than six of them. Hence the command
     iptables -A FORWARD -m set --set test src,dst
    will match packets, for which (depending on the type of the set) the source address or port number of the packet can be found in the specified set. If there is a binding belonging to the mached set element or there is a default binding for the given set, then the rule will match the packet only if additionally (depending on the type of the set) the destination address or port number of the packet can be found in the set according to the binding.