Optical Gel is a simple, easy to install, and proven to repel a wide variety of birds: pigeons, woodpeckers, sparrows, gulls, crows, starlings, mud swallows and more. Optical Gel is made of all-natural, 100% safe ingredients. Ingredients are a proprietary blend of citronella, mint oil, agar, and beeswax create an unpleasant feeling for the birds, having a sticky texture and scent that keeps birds away. Optical Gel works on 3-defense mechanisms: sight, smell, and touch. When light reflects off the optical Gel, birds see it as fire or something dangerous and leave. If they pass this fear, they do not like the smell deterring them from the area. Lastly, if they passed the first 2, the third mechanism is when they touch the material they do not like the feel of the gel and leave the site. Optical Gel is proven in all climates and typically works 2-4-years and in some cases much longer. Simply install optical gel based by looking at our spacing chart to determine what is appropriate spacing for your situation. Use on ledges, signs, balconies, soffits, beams, skylights, signs, roofs, HVAC equipment, enclosed spaces, etc. Optical Gel 200-pack includes: 200-Optical Gel pods (glue not included).