these photoluminescent signs absorb and store energy from ambient fluorescent light. Signs are easily visible in the event of a sudden blackout. Signs are ul924-listed by underwriters laboratories. Non-electrical, non-radioactive signs are maintenance free; no mechanical or electrical power source required and will last 25+ years. Meet nfpa 101 – life safety code, jcaho and osha requirements. Meet current building codes including ibc, ifc, icbo, boca, sbcci and nfpa. Leed qualifier. 50-foot viewing distance. Each double-sided sign comes with four self-adhesive chevron stickers that installer peel-and-stick applies on-site if directional indication to the left and/or right is needed. Easy do-it-yourself installation = no electrician needed. Sign comes with one set of two mounting clips that installer can attach to two top holes for ceiling mount, or attach to two side holes for flag mount. Mounting screws not included in sign package.