Two remote controlled motion alarms (one on the chain lock and one hidden on the bike.) And i use a chain recommended by the lock picking lawyer (lock picking YouTube channel). Never had a problem. The alarm on the chain is to let the thief know as soon as he check the chain that the bike has an alarm. Second alarm is Incase they decide to cut the chain one, both alarm wi continue to ring and the hidden one will continue ringing after the thief breaks the first one. Just the alarm on the chain will scare most thieves.
Kryptonite Evolution 1016 Mini 10mm Chain Bicycle Lock https://smile.amazon.com/dp/B007EW31R6/ref=cm_sw_r_apan_glt_fabc_Z5JTCSAB3ZMFXFWP6GTY?_encoding=UTF8&psc=1