One of my personal favourites, the Head Halter is a type of collar which is used for controlling the dogs skull instead of the neck. Highly advisable for owners whose giant dogs are potentially stronger than them at times.
Pro: Uses the dogs own momentum to restrain him. Closes the mouth when necessary, otherwise keeps relaxed. Con: Resembles a muzzle which sometimes puts off observers and scares people of a dog with a Halti.