If your baby carrier comes with such elastic bands on the waistband or shoulder straps, remember to put the buckles through them. These act as an additional protection.
1) Elastic band sewn onto the ends of waistband or shoulder straps.
2) Put the buckle through it. Bring the extra strap above the elastic band so that the buckle will not slide off in case of accidents.
3) The buckle should not slide off when loosen.