personalized gun lock

[robert_huff]

[my brain zombie morning]

Context: Real Life

Terms searched: Wikipedia: "gun safety", "gun lock"

There is a mechanism for securing a gun that involves additions to the action so it will only fire in the )very close) presence of a specific object (usually a ring worn on the shooting hand).

I am blocking on either a generic term for this or specific make/model names. Can someone please help?

Thanks.