An antifreeze system sprinkler is a great way to protect and is easy to maintain. The antifreeze system is similar to a wet system except the water has been mixed with an antifreeze solution that is of food grade (Propylene Glycol or Glycerin).
A wet system simply means that it is full of water and if a head is opened water will flow out and spray the area. In an antifreeze system the antifreeze will flow out then be replaced by the water source. In colder temperatures it is very important to service quickly or to heat the area above freezing.