The F-Tube is one of our rectangle storage tubes and measures 1/2" by 1 9/16th's with an adjustable length of 5" when closed and about 8" when extended. 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.