What does the back look like and measurements of back opening?

There is no back to this item....just a couple of support pieces. Very flimsy!

Thank you for your question There is no back in the product. You have full access for the plumbing lines and drain pipe. Thanks for the interest in our products

Thank you for your question There is no back in the product. You have full access for the plumbing lines and drain pipe, Thanks for the interest in our products