This is largest diameter we use: a full inside of 1 & 1/4 inch square, with a fully closed length of 5 inches. Remember it expands in length if required! This offering is for a group of 5 tubes in this size. When we started packaging products, we wanted to use a container that was more useful than a tiny cardboard box. Something was needed that would serve its purpose protecting the product that we made for you, but could also be adopted for further use. I think we must have done well in our selection because we have received so many requests from locksmiths that love these semi-transparent containers that we now make these slip over tubes available to you.