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Bedshe via Amazon takes 50% off the Diamond-Pattern Duvet Cover Set in various sizes and colors via coupon code "AMMFSLD4"
Shipping: Prime members receive free shipping on all sizes. (Orders over $ 25 before coupon net free shipping for everyone.)
Sizes with prices after coupon:
Twin https://www.amazon.com/dp/B072PQWJZ8 for $ 9.99
Queen https://www.amazon.com/dp/B071Y2X7N for $ 13.49
King https://www.amazon.com/dp/B071LLXRCL for $ 14.99