A 3-in-1 jacket, also known as an 'interactive' or 'IA' jacket, consists of a waterproof outer shell and a detachable inner fleece – making it the ideal choice for an all-year-round jacket that can tackle changeable weather conditions head-on.
Wear the waterproof outer layer
The outer layer of a 3-in-1 jacket should be made from a waterproof, breathable synthetic material. It should also have been treated with a water repellent finish, which will allow rain or water to roll off the surface. The outer layer can be worn on its own in mild or wet weather when you just need some quick protection against the elements.
Wear the insulating inner layer
The inner jacket is the insulating layer. This is made up of a warm material such as fleece or a synthetic, polyester filling. This layer can be worn alone when you just want to stay warm.
Wear them both together
A good 3-in-1 jacket can provide you with all the protection you'll ever need from the elements. However, when the weather gets particularly bad you can wear both the fleece AND the outer layer together for ultimate protection. The inner layer and outer shell are usually zipped together, however, they are sometimes attached using buttons or hooks.