What are the pop filters for the CM-311A?

I traded up my CM-312A for a CM-311A.I noticed that there are three available pop screens. I don't understand the terms "2-stage/multi-stage."
Mark Boucher

Reply: The standard pop filter that comes with the CM-311A is the best choice for musical use because it gives the most gain before feedback. Its model number is WS-6, and it is a simple foam hemisphere.

The WS-13 is a multi-stage pop filter for broadcasters who don't need the gain-before-feedback, but need extra pop protection. It has a flat foam disk in front of a foam windscreen, and inside that foam windscreen is another foam liner of lower density. So it has three stages of pop protection.

The WS-14 is a 2-stage windscreen for broadcasters who need wind protection outdoors. It is a large foam windscreen with a low-density foam liner.