Our Bolt on Climbing Holds come in variety of 250 different shapes and range from the size of a golf ball to a baseball. These holds have one hole and are designed to be used with 3/4 inch plywood. The holds include hardware for mounting: 3/8th T nuts and 3/8th 1.75 inch Alloy Socket Cap Allen Head Bolts. Rocky Mountain Climbing Gear is proud to offer you durable, realistic, long lasting products. We know that you will enjoy years of climbing fun! There are some things you will notice about our “rocks” that are different from other climbing holds you may have used in the past. Rocky Mountain Climbing Holds are manufactured in the United States. Our Holds are made from recycled plastic material. By buying these holds you are keeping plastics out of landfills. Thank you for helping us go green! You may notice a slight smell on the holds. This is normal and from the manufacturing process. This smell is not harmful and will go away within a few days. If this does happen to your product, run the rock holds through the dishwasher and let air dry. Some color differences in your climbing holds are normal and due to the material that they are made from. We take pride in the products that we offer, and we also take pride in our customer service.