Automatic (Standard) This system is designed to activate when the user is immersed in the water. They are highly effecient and will inflate within seconds. They also have a a manual lanyard should you wish to inflate by hand. Can, on occasion, inflate inadvertently if the user is exposed to heavy spay or rain.
Automatic (Hammar) This system uses a firing mechanism that relies on water pressure to inflate the jacket. It will not inflate untill immersed in 10cms, or more, for 2 to 3 seconds. This has the obvious benefit to any user who will often be in contact with heavy rain or spray and wants to avoid inadvertent inflation. Infation will only happen when the user is in more than 10cms of water. When you want it! They also have a manual lanyard.
Manual systems have no automation and must be activated by the user pulling the lanyard. These jackets will not automatically inflate if the user falls into water. Useful if the wearer is going to be in and out of water launching and retrieving small boats for example.