def get_all_reserved_instances_offerings(self, reserved_instances_id=None,
                                             instance_type=None,
                                             availability_zone=None,
                                             product_description=None,
                                             filters=None):
        """
        Describes Reserved Instance offerings that are available for purchase.

        :type reserved_instances_id: str
        :param reserved_instances_id: Displays Reserved Instances with the
                                      specified offering IDs.

        :type instance_type: str
        :param instance_type: Displays Reserved Instances of the specified
                              instance type.

        :type availability_zone: str
        :param availability_zone: Displays Reserved Instances within the
                                  specified Availability Zone.

        :type product_description: str
        :param product_description: Displays Reserved Instances with the
                                    specified product description.

        :type filters: dict
        :param filters: Optional filters that can be used to limit
                        the results returned.  Filters are provided
                        in the form of a dictionary consisting of
                        filter names as the key and filter values
                        as the value.  The set of allowable filter
                        names/values is dependent on the request
                        being performed.  Check the EC2 API guide
                        for details.

        :rtype: list
        :return: A list of :class:`boto.ec2.reservedinstance.ReservedInstancesOffering`
        """
        params = {}
        if reserved_instances_id:
            params['ReservedInstancesId'] = reserved_instances_id
        if instance_type:
            params['InstanceType'] = instance_type
        if availability_zone:
            params['AvailabilityZone'] = availability_zone
        if product_description:
            params['ProductDescription'] = product_description
        if filters:
            self.build_filter_params(params, filters)

        return self.get_list('DescribeReservedInstancesOfferings',
                             params, [('item', ReservedInstancesOffering)],
                             verb='POST')