Description They are easily applied with a screw and Phillips screwdriver. The screws are supplied with this item. Each spike has a tap on the bottom in which the screw is applied.  Description and Specs:height: approx. 1 inch, 28 mmbase diameter: 3/8 inch, 9.5 mmmaterial: nickel over zincfinish: nickelcolor: silverscrew type: inch 8-32, 1/4″ length threadshape: round coneBag size: 20 spikes