Soft structured carriers are sometimes called buckle carriers, because the usually adjust with a series of buckles and straps that are similar to those on a backpack. The adjustability provided by these straps and buckles means parents of very different sizes can often use the same baby carrier.
Sometimes a soft structured baby carrier might also be called a front pack. However, unlike the old-style front pack carriers, you can usually wear a soft structured carrier on your back, too. Some soft structured carriers, such as the ErgoBaby, also allow you to wear baby in a hip carry.
Soft structured baby carriers have two straps that go over the parent's shoulders. These are usually padded in some way for comfort. The straps adjust with webbing like a backpack. There is usually a waist strap that is adjustable, as well, and a chest strap to hold the shoulder pieces in position.
This type of baby carrier is designed to distribute the baby's weight equally over the parent's shoulders and hips. In general, you can use a soft structured baby carrier from the time your baby can hold up his or her head up. The upper weight limit of this type of carrier often accommodates kids through the toddler years. Several baby carrier companies offer an insert to help cradle a newborn inside the larger soft structured carrier, as well.