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 sign comes with two 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 has 4 holes: use screws or nails (not included in sign package) for flat wall mount. Suited for high-location and floor-proximity installation.