This SPF/UPF 100+ Nylon Lycra jacket style zip top is designed with elbow length sleeves, full length zip, side panels for a more flattering form and a collar. Many imitations have a crew neck leaving delicate parts of the neck unnecessarily exposed. Zips are nylon heavy duty. Seams are flat stitched with a six needle machine for strength and endurance. We use Coats Patons corespun nylon, the best thread in the world for swimwear.