Icebreaker SIREN SS SWEETHEART is a soft and stretchy women’s T-shirt with an improved fit and corespun technology that you will not want to take off. It is comfortable, stylish and suitable for casual wear and layering. Corespun technology spins a super-thin nylon core around traditional merino wool That way it improves the strength and durability of the fabric while maintaining its softness. It can be worn all year round, while travelling, hiking or just relaxing after a demanding day outdoors. Soft V-neck and slim fit design is very versatile.