Alternating tone 131 Alternating tone, UK BS 5839-1 (fire alarm, railway crossing) 142 Alternating tone 146 Alternating tone, France NFS 32-001 (fire alarm) 1 Powerful electronic sounders Certified for hazardous [...] Stainless steel bracket permits ease of installation for any orientation. 1 Powerful electronic sounders 2 ATEX certified for zones 1, 2, 21 and 22 3 Choice of output level and tone 4 IP 66/67 enclosure rating [...] aluminium LM6, horn made of ABS stainless steel mounting bracket for 360° positioning categories 2G (zones 1 and 2), 2D (zones 21 and 22) operating between +70 / –50 °C protection system protection system BExS110D