Our frames are always 3 cm thick, with the exception of our 2 smallest sizes: 20 x 20 cm and 20 x 30 cm. Due to their ratio they are 2 cm thick. We have chosen to use 3 cm thick frames because they are sturdy and give a good quality result. At the same time the chances of the frame warping is very small with a 3 cm thick frame. But most importantly, this looks great on your wall!