In order to understand the many uses and advantages of a 4x4 closure, it is important to note all the many pros as well as the few cons. See below for more info.
 
Pros

• Realistic looking hairline. From the very start, 4x4 lace closures were designed to help women all over the world achieve the most natural and realistic hairline possible. Made from transparent or HD lace, a 4x4 closure will blend really well with any skin tone and make your hairstyle as flawless as ever.
• Easy installation and removal process. With just 4 inches of lace to work with, you will be able to both install and remove a 4x4 closure with ease. This also means that you won’t have to worry about making trips to the hair salon. You can easily apply and remove a 4x4 lace closure by yourself and at your own convenience.
• Inexpensive. Compared to a 13x4 lace frontal or other lace pieces, a 4x4 lace closure is by far the least expensive of them all. This is simply because a 4x4 closure has less lace in comparison to the rest. Therefore, its cost is less in terms of the use of materials used during the manufacturing process. 

• Limited parting space. Though many 4x4 closures provide all that you may ever want, the only thing lacking is its limited parting space compared to a frontal or a bigger closure piece.
• Lack of versatility. Usually, 4x4 closures are parted in the middle. Again, this is partly because of its limited parting space.