Binders are made to offer moderate compression to the chest. Some are made to be used under clothes and some are opaque and can be used to swim. The inner powermesh layer(s) offers moderate binding while allowing for some flexibility to make sure breathing is not restricted. It's best to note how much compression you're looking for when you order, however, some binders only offer light or moderate compression.
Binders will fit very tightly when you first get them, and will relax over the first few wears.