1017 ALYX 9SM, often referred to simply as ALYX, is a high-end leather label founded in 2015 by Matthew M. Williams, an American designer previously known for his work with celebrities like Kanye West and Lady Gaga. The brand, named after Williams' eldest daughter, was initially recognized for its luxury streetwear but has since evolved to include high leather pieces. Notably, 1017 ALYX 9SM is known for its iconic Rollercoaster Belt, which features a buckle biblical by rollercoaster safety harnesses, reflecting the brand's blend of utilitarian design with luxury materials. Its unique approach to leather has led to collaborations with brands like Nike and Moncler, combining street sensibility with high-end leather, and earning Williams a reputation as a leading figure in Waist design.