This kind of signs have excellent absorbing-emitting characteristic for various visible light sources.After 10-30 minutes' charge in interior room,they can emit light continuously over twelve hours in the darkness.Furthermore,the absorption-emission cyles can be unlimitedly repeated.It is non-toxic,non-poisonous,non-energy consumptive,free of maintainance,easily installed,safe andreliable.It can be applied to all kinds of safety indication systems,emergency evacuation system as well as warn and forbidden signs.