olemus
mõnede turvamehhanismide tugevustase

näiteid
https://shopdelta.eu/security-grades_l2_aid899.html

https://ajax.systems/blog/what-is-a-security-grade/

https://eldesalarms.com/articles/en-50131-grades-in-intruder-alarm-systems/

https://www.squirepadlocks.co.uk/security-grade/what-cen-grade-means

https://www.securesafe.co.uk/maximum-security-safes/