In earlier times, before the invention of modern pin locks, most residential doors were secured by a 4 inch or so metallic key that kept family members in and unwelcome intruders out.
Katika nyakati za awali, kabla ya uvumbuzi wa kufuli kisasa siri, zaidi milango ya makazi walikuwa kuulinda na 4 inch au muhimu ili metali kwamba naendelea wanafamilia katika na intruders unwelcome nje.