Not challenging penalty , challenging that we tipped it <| sep |> Quick technical note on single cylinder vs . double cylinder locks . If there are windows on or near the door , a double cylinder lock may help slow down a burglar versus a single cylinder smash window , grab thumbturn , open door . However , a double cylinder lock presents a life safety hazard to occupants , in which case a key should be left in the lock and , honestly , who remembers to do this every night ? , or one left on a hook near the floor next to the door for ease of access during a fire . The other options would include reinforcing the windows and replacing glass with tempered glass , Plexiglas , or one of the security films that help keep glass in place when smashed . Be advised that , while more expensive , a high security lock isn ' t just a better lock , it ' s better engineering and a better bolt a longer throw , a roll pin to defeat cutting attacks , a shroud to prevent icepick attacks , and so on . At that point , it becomes a matter of the strike and the frame to withstand a kickin attack and another user has addressed those . But be certain to anchor the strike with the superlong screws that come in the box the strike should be anchored into a wall stud , and those screws need a pilot hole to keep from splitting the wood , and a bit of lube soap or similar to get them driven home . Also note that a high security lock will ideally be covered under patent , so the key blanks aren ' t available for duplication . This is important for when you loan friends or family a key to feed your dog while you ' re out , and then make a duplicate that you don ' t know about . Six months later , one of your pistols is missing and it turns out that Jethro decided to use a duplicate key to help himself to your HK collection . While a dedicated potential thief could 3 D print or machine or cast a duplicate , keeping Jethro from have a dupe cut at a hardware store will reduce that risk . And many years ago , I worked for a locksmith that would keep and hold keys from secure systems ASSA , Sargeant that were brought in for duplication . We ' ll hold this and give it to your bosssupervisor when he comes in for it .