Our bird spikes prevent birds from perching. They can be applied quickly and easily. They never need reapplication. They will not harm birds and they are cost effective. They also last indefinitely. Bird spikes block pest birds from their roof "landing strips" with the most effective "keep off" sign you can post. This is the best spike system for eliminating unsightly bird droppings and health related problems. Bird spike products are currently being used by millions of people and companies worldwide.