Specific installation steps: (1). Seatbelt tightening set: retreat from buckle. Push the red button of lock catch, and take the two inserts out. Select proper seat belt hole according to children` s height, before doing so, please take seatbelt strip, which is at the back of safety chair, out from seatbelt fastened buckle, which is at the bottom of chair, and from the adjustment buckle for the other seatbelt, then loosen the adjustment buckle, pull the two seatbelts in front of safety chair and buckle the appropriate hole, refasten the shorter seat belt adjustment buckle. Place children in safety chair, and put the crotch pad and lock catch between two legs, if it is too tight, loosen the buckle at the bottom of the chair, move it forward for one position and fasten the buckle in related location, place the two seatbelts in front of the chest by putting them through the two arms together with the shoulder pads.Thrust the two inserts into lock catch forcibly, put the back seatbelt strip through enforced buckle, which is at the bottom of chair, and bypass the buckle for the other seatbelt to adjust tightening, two-finger-width left between seatbelt and children would be appropriate.Frap the back seatbelt strip in buckle, push the red button of lock catch, get the inserts out and take the baby out, the tightening for your children is fixed now.