The System Sensor SpectrAlert Advance color lens attachments come in four colors-amber, blue, green and red-for mass notification, severe weather, emergency response and other non-fire applications. The lenses easily attach to any plain (non-FIRE-printed) SpectrAlert Advance strobes horn strobes, speaker strobes and strobe-only devices. The lenses may be used with wall or ceiling strobes in indoor or outdoor applications.Each lens ships with a clear adhesive on the bottom surface. The lens is then aligned with the clear strobe and applied.