I am a professional Wildlife and Landscape Photographer now living near Nelson in New Zealand
This a set of 3 high quality archival images each about 5" (123mm) Square and 9mm thick and come in their own gift box. Each block has black edges and a slot routed in the back for mounting. All block have 3 coats of lacquer to protect against light moisture in bathrooms or kitchens.

5" blocks Are 56% bigger than the 4" (100mm) version mostly sold on trade me.

With over 3000 sets sold I have found most of my customers prefer the thinner lighter blocks for posting overseas.