These virtually indestructible covers (slotted for horn or speaker units and solid for strobe-only alarms) are designed to stop vandalism and accidental damage. Molded of clear, thick, UV-stabilized polycarbonate material, they are backed by a three year guarantee against breakage in normal use. Slots in the STI-1210, 1215, 1217 and 1219 allow the horn to be heard. The STI-1221, 1225, 1227 and 1229 are for strobes only. Many tough, clear spacers are available for larger strobe/horn units, retrofits, surface- mount and weather resistant applications.