Select "Yes" if you want to TRY make filtering in your shop by AJAX. Not compatible for 100{bbackup_94402fb9ba80f392e0976ece85f92b2b876bfcaed8d83250cc06083f7139c7d9} of all wp themes, so test it well if you are going to buy premium version of the plugin because incompatibility is not fixable!