Sibby. Sibi classicbeauty is the most professional high-end brand of precision plastic underwear in China. Sibi precision body shaping underwear uses the principle of imitating the molecular structure of human collagen, contains natural cotton, is super elastic with human skin, and achieves the effect of efficient and comfortable shaping. During physical activity, the fabric naturally fits the body, and even if you sleep in it, you won't feel uncomfortable.