I purchased these socks for my husband, knowing he would love them! I received a pair in my Birchbox, and I loved them because they don't "sink" into your shoes on the heel. There's a "tongue" on the back of the socks that prevents that from occurring. My husband and I work out and run often, and that is a huge problem for us. These socks are the best! They also wash well and do not shrink. Very durable and the colors are awesome! I liked them so much, I purchased more for myself and my husband. Thanks Birchbox, for such a great product!