WooCommerce Forms – multiselect guidance.

I’m adding extra fields to the checkout page in WooCommerce, I can add basic fields like a text box, but need to add a (multi) select box, where the user can choose multiple items. I’ve figured out how to add a select box through code, like this:

add_action('woocommerce_after_order_notes', 'my_custom_checkout_field');

function my_custom_checkout_field( $checkout ) {

echo '<div id="my_custom_checkout_field"><h3>'.__('My Field').'</h3>';

woocommerce_form_field( 'my_field_name', array(
    'type'          => 'select',
    'class'         => array('my-field-class form-row-wide'),
    'label'         => __('Fill in this field'),
    'placeholder'       => __('Enter something'),
    'options'           => array(
        'Buick' => __('Buick', 'woocommerce' ),
        'Ford' => __('Ford', 'woocommerce' )
    )
    ), $checkout->get_value( 'my_field_name' ));

echo '</div>';
}

But that’s just a single select drop down. Can I do something similar for a multi-select? Or do you have a WooCommerce extension that’d you recommend?

Please advice, thanks in advance! Aaron