woocommerce-multiple-select

```php
/**
 * Custom fields in Woocommerce product
 */
function vads_create_custom_fields() {
	global $post;
	$pictograms = (array) get_post_meta( $post->ID, '_pictograms', true );
	?><p class='form-field _pictograms'>
    <label for='_pictograms'><?php _e( 'Pictograms', 'woocommerce' ); ?></label>
    <select name='_pictograms[]' class='wc-enhanced-select' multiple='multiple' style='width: 80%;'>
        <option <?php selected( in_array( 'picto-1', $pictograms ) ); ?> value='picto-1'>Picto 1</option>
        <option <?php selected( in_array( 'picto-2', $pictograms ) ); ?> value='picto-2'>Picto 2</option>
        <option <?php selected( in_array( 'picto-3', $pictograms ) ); ?> value='picto-3'>Picto 3</option>
        <option <?php selected( in_array( 'picto-4', $pictograms ) ); ?> value='picto-4'>Picto 4</option>
    </select>
    <img class='help_tip' data-tip="<?php _e( 'Select multiple pictograms', 'woocommerce' ); ?>" src='<?php echo esc_url( WC()->plugin_url() ); ?>/assets/images/help.png' height='16' width='16'>
    </p>
	<?php
}
add_action( 'woocommerce_product_options_general_product_data', 'vads_create_custom_fields' );

function vads_save_custom_fields() {
	global $post;
	$woocommerce_pictograms_field = $_POST['_pictograms'];
	array_walk($woocommerce_pictograms_field, 'esc_attr');
	update_post_meta( $post->ID, '_pictograms', $woocommerce_pictograms_field );
}
add_action('woocommerce_process_product_meta', 'vads_save_custom_fields');

```