E4 Neoprene makes this suit 30% more flexible and 20% lighter. The E4 Flash lining has two layers that funnel water out of the suit once it's hung up. It is one of the warmest and comfortable linings available. The internal seams are taped with E4 super stretch tape, which gives stretch while still sealing the seams and maintaining comfort. No wonder this suit is a Three Time SIMA Award Winner!