It joins these two.
8"x10" and 3"x5"
There is a video on the Gelli Arts blog on using the round Gelli - take a look here.
This is my second play time. I didn't follow the instructions... instead I stamped the entire page with solid block colours, overlapping. Then laid various stencils on top and stamped through with the Gelli. Quite pleased with my effort.
I have loads of stencils... and got a bit carried away the other day cutting files on my Silhouette Portrait. Thought I'd cut 15 stencils, but actually when I added it up, its nearer 21! Some free files and some purchases from the Silhouette Store.