Bate and switch?
I think it's misleading. The photo shows a stretched canvas, while in smaller print below it says rolled.
So how many unhappy customers (because people don't read the details) are going to be contacting you because their little canvas is useless without the stretchers?
Yep, that's called "False Advertising", showing a mounted/stretched canvas in the ad, and then later when the customer receives their rolled up print instead of what is featured in the ad, they will NOT be a happy customer, kind of like bate a switch.
I know I would not be very happy, and I'll bet most of your customers will be upset with you.
It's best to be upfront, and show the customer what they will actually be receiving for their $4.95, like on the website listed below, they clearly show what you get and also have up-charge options for mounting like you are featuring in your ad.
http://www.photos2canvas2u.com/rolledprints.html