3 bundle hair deals is the most common tie-in sale, because usually 3 bundles can make a full head. Sometimes it will be sold with hair extensions, such as lace closure, lace frontal, lace wigs etc. Those tie-in sale is cheaper than what you buy respectively. And our hair is made of 100% virgin human hair, very soft and natural as install. For a full install 18 inches or shorter, we recommend three bundles. However for the styles that longer than 18 inches, we recommend you to use 4 bundles to achieve a full look, because the longer the hair you buy, the shorter the weft is.