one can quick shop the product if one knows sku , product name ,mpn, isbn, upc. just type and autocomplete will fill it , just click on + sign and you are done.It is responsive and works good with large screens and medium sized screens.
you can also remove added product easily. It works well with opencart default structure .
A great utility. Made by shambhal who holds excellent reviews on freelancer.com for opencart customization.
Please note that if you added some modules contrary to opencart default add to cart feature , it might not work.With extra fees it could be made compatible but that is not mandatory for developer.