FedEx and USPS - Skip product from shipping package

functions.php

add_filter('wf_shipping_skip_product','skip_my_products',10,3);

function skip_my_products($skip = false, $product, $package){
	$shipping_free_classes = array(16); // array of shipping class ids to exclude from cart
	
	$shipping_class = $product['data']->get_shipping_class_id();
	
	if(in_array($shipping_class, $shipping_free_classes)){
		$skip = true;
	}
	return $skip;
}