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Reference.org
Protector lock
open-in-new
<p>The term protector lock has referred to two unrelated <a href="/facts/Lock_(security_device)/5xcFqSyy">lock</a> designs, one invented in the 1850s by <a href="/facts/Alfred_Charles_Hobbs/Ak9ATNjH">Alfred Hobbs</a>, the other in 1874 by Theodor Kromer. </p>