A client of us needed an invoicing system for their website and instead of developing it ourselves we purchased this extension, it does exactly what the client required. We ended up using it on another client's site and we have installed it on our own server to make our invoices to send to our client's email. A real asset, highgly recommended. And if you need extra features or have questions the support they offer is really professional, one of the best (and fast!!) I've seen. Very happy.