A real estate lock box is actually a combination lock that uses a code to open a door to a house that the real estate agent is showing for landlords to gain access to a property to make repairs when the tenants are not home.
No one wants to go to work and leave their door unlocked or place a key in a planter and hope a burglar doesn't find it. But, you do want your landlord to get into your apartment or home to make needed repairs while you are away so having a coded lock box on your door or apartment with you and your landlord being the only ones to have the combination allows him to do his job without you taking off work from yours.
It also is handy for emergencies that come up giving your landlord ready access to the property without first having to contact you for and having you rush home with the key. Having this extra feeling of both ready access and security can make it much easier for you and your landlord to get your work done.
Some Real Estate agents also find that gaining the permission of their clients to have a lock box installed in the homes they are trying to sell helps them to show properties to prospective buyers when it is the best time for the buyers to make appointments. One of the most difficult things about selling property is trying co-ordinate the property owners schedule with that of the prospective buyer and even the real estate agent's schedule. By having a lock box accomplishing that scheduling is easier to do because the owner does not have to be home or take time off from work.
If your real estate agent asks permission to have a lock box installed don't worry that he will be bringing people by without your permission. Most real estate agents are professionals and will make arrangements with you to show the house on a given day in your absence. If a prospective buyer should show up the agent will call you to gain your permission before entering the home the lock box simply means that you won't have to leave work to open the door so he can show your home.
While you could just leave a spare key with the real estate agent there is always the possibility that keys can get lost or misplaced. With a real estate lock box, the box is attached to your home and the code is in the file for your home that the agent will take with him when showing the house so there is no fear of lost keys ending up in the wrong hands, or getting lost leaving the agent no way to gain access to your home in case you are at work or on the road.
While there is no guarantee that a lock box will help to sell your home faster it does help to show the home to more prospective buyers.