Material： Made of high-quality PP, strong and durable. can stand any weather and keep stay intact through blizzards and windstorms that will never loosen or rust. SIZE:The length of each spike is 4 inches (100mm) and the width is 2 inches (51mm). can use higher spikes to defend against medium and large birds. Design: The unique high spikes design makes it impossible for animals to stand and stay around, won't cause harm or hurting to animals humans. Easy to Install： There are three ways to install the bird spikes, simply nail the bird control balcony to a flat surface or tie the pigeon control balcony to the surface with a strong cable or glue the double sided tape for bird tips.（Not included accessories） Applicable：Installed on fences, roof, dock, sheds, ledges, walls, terraces, effectively prevent the invasion of small birds and other animals.