A 5 x 5 HD Lace Wig is a type of human hair wig that has a 5 inch by 5 inch (12.7cm x 12.7cm) HD (high-definition) lace base, which is designed to give a more natural and seamless appearance when worn, especially in the hairline area. The wig typically uses 100% human hair, allowing for versatility in styling and a natural look.