sub metric {
    my ($self, $stat, $metric) = @_;

    if ((! defined $metric || ! $metric) && ! $self->_is_metric) {
        $stat = $stat * 3.28084;
        $self->{tpv}{$_} = substr($stat, 0, index($stat, '.') +1 +3);
        $self->_is_metric(1);
    }
}