Eh? The siren is wireless too, literally AC mains to the panel and off you go!
I'm going to be honest, I serviced a Yale system a few weeks ago, it was easy. Changed all the batts too, but they was just standard Alkaline batteries! A intruder alarm needs to be relaible and with that Li-ion batteries should be used too.
At the end of the day, it is DIY and as professional installers shouldnt we be promoting equipment that has years of R+D and capitial plouged into it?