There is a difference between a
life preserver and a PFD.
The
life preservers are required to have aboard the vessel, enough for the maximum number of people that is allowed plus 10%.
The PFDs (Type II, III, or V) that people may wear are good but under the law don't replace the
Life Preserver (type I).
The
Life preservers should be in a readily accessible place. Like the cockpit locker. with nothing stored on top of them. The locker cannot be locked in any manner also. The vessel's name stenciled on them is required also.
Now the other PFDs are worn more often because they are easier to wear.
A Type I will turn an unconscious person over to face up in the water. A type II may turn that person over. Type III & V will probably not turn that person over to the face up position.
The Type IV? These are the throwables such as life rings, cushions, horse shoe float and so on.
But the PFD or
life preserver will only do you good if you are wearing it. So whether you go for an inflatable or close cell Type II or V and or the type I; Wear it when on the boat or transfering from the dock to the boat and back again. It doesn't do you any good in a locker or your luggage when you fall into the water.
Size the
Life preserver and/or the PFD to the person also. Children will enjoy their experience on the water more that way. They don't enjoy it all that much when they are wearing the rectangle
Life preserver. So spend the money for them. Size it correctly and replace it when they out grow it. They are worth the effort & money in getting the correct size just for them.