Refined Core takes classic uppers and updates them with new materials and a sleeker, more sophisticated last - a striking hybridisation of formal and casual. Most obviously appropriate for the spring/summer season is the use of Denim and Fine Twill on all three offerings - for the 3-Eye Shoe and Penny Loafer, this is kept ultra-simple, with neat contrast stitching in a tobacco or yellow tones, waxed cotton laces and subtle slim soles. The 3-Eye also has two aeration holes in the side for a cool summer feel. Penny Loafer. Denim, a traditional twill weave fabric consisting of 60% Cotton 38% Polyester 2% Spandex. Goodyear-welted, the upper and sole are heat-sealed and sewn together.