I had my first mate bike stolen with two locks on (a chain and a silly cable lock) inside an 8 minute window! Police didn’t even check the cctv cams for those 8 mins - to busy with violent crimes. Anyway mate were angels and sent me a new bike and I got an Oxford Alarm D lock (the bright blue ones) which is silver rated and has a 110db alarm on which works a treat. Not even had an o ring pinched since. They’re only £30-50 depending on size D lock & package (they do the usual cable & lock packs) I got the mini. Best £30 I spent & I think it’s now amazons choice...
Oxford Unisex D Duo Max Alarmed Shackle, Black/Blue, One Size https://www.amazon.co.uk/dp/B01DY5RQTU/ref=cm_sw_r_cp_api_i_toFiFbAW79RZ7