Several come with detachable bases. The base stays in the car so you do not need to install it every time you put your baby in the car. The car seat itself locks into the installed base. If more than one parent will be transporting the baby on a regular basis, an additional base can be purchased for installation in the second vehicle. Some infant seats come with more than one harness slot which allows for adjustment as the baby grows.
Infant seats come with carrying handles.
Instructions must be checked for proper placement of these handles during travel. Many convertible seats have two or more buckle positions to allow for extra room for a growing child or bulky clothing. Several convertible seats are now available with higher weight limits for bigger babies. For larger babies, look for a seat that can be used rear-facing up to 25 or 30 pounds. Premature infants or infants with special needs may require special restraint systems.