Core Ribbed Everyday Tank Core Ribbed Everyday Tank 7DIAMONDS Core Ribbed Tank 7Diamonds Ribbed Tank Old Gold Carbon38 Women's 7 Diamonds Core Ribbed Full Length Tank Top 7DIAMONDS Core Ribbed Tank 7Diamonds. Our Core Performance Collection combines our signature 4 Way Stretch fabric with a softer than ever finish that allows for all around comfort in or outside the house. Look good and feel good at your next workout session or morning hike. Details: Care: Machine wash cold with similar colors. Tumble dry low. Iron on low if needed. Composition: 81% Polyester 15% Lyocell 4% Elastane