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 1/4 inch, 30 mmbase diameter: 3/8 inch, 9.5 mmmaterial: nickel plaquefinish: black nickelcolor: blackscrew type: inch #8-32 x 3/8″ length threadshape: standard treeBag size: 20 spikes