The Prairie collection by Nostalgic Warehouse features simple, curved styling popular in the 1920's and 1930's and is modeled after one of the door hardware choices in Sear's Craftsman Kit homes. The style has been modified slightly to fit on modern pre-drilled doors. A mortised door is usually an older door that has a longer, more narrow lock body and can be used as a passage or privacy door set. To use it as privacy, you have a skeleton key that unlocks and locks from both sides of the door. To use it as passage, you would simply not use the key or lock the door.