Defeat the winter chill with this ultralight SIMIYA thermal underwear set, engineered with a high-performance blend of 92% microfiber and 8% spandex for a superior slim fit. The interior features a dense, soft fleece warming layer that traps body heat effectively, making this long-sleeved shirt and pants set an essential base layer for skiing, trekking, or daily commutes. Designed with four-way stretch technology, the fabric moves with your body to ensure full mobility without sagging or bunching. Reinforced seams and a tagless interior eliminate skin irritation and chafing, while the practical fly opening in the pants adds functional convenience for all-day wear. This machine-washable thermal set maintains its shape and insulating properties even after multiple cycles, offering a durable solution for harsh weather conditions. The pull-on design and smooth exterior allow it to slide effortlessly under jeans or work trousers without adding bulk, while the neutral black color provides a clean, professional aesthetic. Available in size Medium, the moisture-wicking properties of the microfiber help regulate your temperature during high-intensity outdoor activities. Whether used as professional sportswear or cozy loungewear, this set combines reinforced construction with an ultralight feel to keep you warm and comfortable throughout the coldest months.