private function get_sub_field( $field, $index ) {

		$field['id'] .= '_' . $index;

		if ( isset( $field['controller'] ) ) {
			$field['controller'] .= '_' . $index;
		}

		$name = ucfirst(
			strtr(
				preg_replace_callback(
					'/(\w+)/',
					function( $m ) {
						return ucfirst( $m[1] );
					},
					$field['type']
				),
				'-',
				'_'
			)
		);

		$field_class_name = str_replace( '{TOKEN}', $name, 'LLMS_Metabox_{TOKEN}_Field' );
		$field_class      = new $field_class_name( $field );
		ob_start();
		$field_class->output();
		return ob_get_clean();

	}