It is a bottlenecked centerfire cartridge that is somewhat similar to the .22 Hornet in power....
FN's 5.7×28mm firearms—the P90 personal defense weapon and Five-seven pistol—are in service with military and police forces in over 40 nations throughout the world. In the United States, 5.7×28mm firearms are currently used by numerous law enforcement agencies, including the U.S. Secret Service
For home defense other than a shotgun its a very good cartridge....
