The kidde professional series 230 volt carbon monoxide alarm has an lcd display showing the peak level of co detected the alarm has a memory to store the peak level and has a sealed in rechargeable lithium ion battery for backup the alarm has a testreset button and can be interconnected to kidde k10c k20c and k30c professional series mains smoke and heat alarms suitable for wall or ceiling mounting please note this alarm must be fitted by a qualified electrician