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, surfacemount and weather resistant applications. For the STI-1210/1221 series, spacer A has a four inch deep enclosed backbox, spacer B has an enclosed backbox molded with an integral double-gang outlet box. Spacer C has an open back for retrofit applications. Spacer D accommodates deeper units and applications with exposed conduit electrical connections. Spacer E has an open back frame for flush-mount applications. An appliance mounting plate comes with the STI-1219/1229. Unique Enviro Kits are available for extreme conditions where dampness or water is present.