FINE:
Gauge: Triangular fine 40
Barbs on 3 sides. A fine needle for detail work and getting a neat surface. Best not to use it when working with coarse fibres or for rough sculpting/bulk work.
MEDIUM:
Gauge: Triangular medium 36
Barbs on three sides. A good needle for making the bulk of a 3D piece and again, attaching pieces well. Not good for any detail work.
COARSE:
Gauge: Triangular Coarse 32
Barbs on 3 sides. This is a sturdy needle good for working with course fibres and firmly attaching pieces. Not great for detail or a neat surface.
REVERSE:
Gauge: 36
The barbs go the opposite direction which results in fibre being pulled out. This is useful to create a fluffy finish on well felted pieces.
SPIRAL:
Gauge: 36 spiral
The needles are twisted which makes felting faster while reducing the surface holes other needles make.
STAR:
Gauge: 38
With barbs on four sides it is a great all round needle, good for finer work and finer wools as well as bulky sculpting work.