Kids wetsuits, for sizing most youth wetsuits are close to the age of the child, but please check the available size charts if your unsure. The 3/2mm stands for the thickness of the neoprene, a 3/2 would generally have 3mm neoprene on the chest, back and leg panels, while leaving 2mm neoprene on the arms and shoulders to create an easier swimming or surfing movement.
One huge factor in the warmth of a wetsuit 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 wetsuit. 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.
When you’re looking for wetsuits for kids it’s hard to get a proper tight fit, without them growing out of the wetsuit in 2 weeks, but just remember the tighter it is around the chest and back panel the warmer they will be. Most toddler wetsuits are a bit looser, but are great for keeping the sun off and windchill away. They also give a little flotation for added confidence in the water.