These blocks/risers/bases are clear transparent acrylic. They are all 3/4" thick. Please look at our other listings for thicker bases/risers. They all come with silicone bump-ons on the four corners of the bottom to protect the acrylic from getting scratched and to keep the base in place firmly. All of our bases come hand polished not by machine so all the corners are square and flat. Our bases can be found in homes under statues and art pieces and in museums all over the country showcasing whatever object is placed on them. We have attached pictures for your interest. We have been around since 1963 so purchase with confidence that you will receive a beautiful perfect piece. We do all our own work and we carry in stock acrylic from 1/16" thru 4.00" to service our customers properly. We have made base as thick as 12.00" before so any size or shape is no problem.