RED HEART-Heat Wave. Heat Wave is a revolutionary yarn that is activated by sunlight, even on a cloudy day, to keep you up to 12 degrees F warmer. Upgrade your outdoor gear and stay warm at sporting events, everyday outdoor activities or even walking your dog. Made in the USA, Heat Wave features a classic and versatile range of solids. Weight category: 5. Content: 100% acrylic. Putup: 3.5oz/100g, 198yd/181m. Gauge: 16sx21r = 4in/10cm on size US8/5mm knitting needles. Suggested crochet hook: USI9/5.5mm. Dyelotted: we try but are not always able to match dyelots. Care: machine wash warm, gentle cycle, Tumble dry low, do not over dry. Do not bleach, do not iron. Comes in a variety of colors. Each sold separarely. Made in USA.