Wetsuits from the best brands in the world at great everyday prices. General info : 4/3mm stands for the thickness of the neoprene, a 4/3 would generally have 4mm neoprene on the chest, back and leg panels, while leaving 3mm neoprene on the arms and shoulders to create an easier swimming or surfing movement. Another huge factor in the warmth of a suit is the stitching areas, a suit that has GBS seams ( glued and blind stitched ) has had all the panels glued together and the stitch line has not gone all the way through the neoprene, this slows the water transfer coming through the seams giving the body more time to warm the suit. A flat locked stitched suit has had thousands of holes punched though the neoprene which allows water to come through, its a great strong, cheap and comfortable way of making a suit. The ultimate warmth comes from taping over the suit seams, this creates an almost water tight seal, but is also reflective in the price of these suits. NZ winter wetsuits in the south Island are usually a minimum 4/3mm thickness. A good 3/2mm will get you through in the upper north during the colder months.