One of the first designs had straps that held the padded seat against the rear passenger seat.

Within the seat, the child was restrained by a Y-shaped harness that slipped over its head and both shoulders and fastened between the legs.

These seats confined the children, raised them above the level of the passenger seat, and made them more visible to adults from the front seat.

Other designs to accommodate growing children followed quickly over the next several years.

Fabrics and vinyls are used to make safety seat covers and harnesses.

The harnesses meet the same strength requirements as those for adult seat belts.

Pads and covers are sewn by the child safety seat manufacturer or by outside suppliers.

Child car seats are tested through a crash test process.

After the crash test, the seat must still meet certain performance criteria like buckle release pressure.

Special anchor attachments will be added in the future to safety seats that will secure them to new anchors in the vehicles and reduce the problem of using the safety belt to secure the child seat to the car seat.

Charts of average child sizes within particular age and weight ranges help designers fit the seat to the child and make it comfortable.

Purchasers prefer infant seats with lighter colors of fabrics and child-like patterns whereas seats for older children tend to match trends in vehicle design, including darker colors and more sophisticated patterns that are coordinated with vehicle interiors.

Both covers and harnesses have to be able to withstand flammability tests, but they also have to be washable.

Only mild soap and water can be used because detergents or chemicals break down the flame resistant fabric treatments.

Types of foams are heavily regulated to meet standards for flame resistance and energy absorption.