... that to prevent fire,thanks. smoke alarm AK-218A4Description:1, Power:110VAC/220VAC/230VAC( backup 9v ... (normal) and 20-50 mA(alarm working)3,Sensitivity to smoke:In comply with UL217 &BS5446: Part 1 20004,Kite mark ... 10,Package size:58.5cm*42.5cm*30.6cm11,Quantity/BOX:80pcs12,CtnWei(kg):15kg13,Q`CTY/20`FT:33920pcs