The box should contain one double back, two single bases and two head rests.
First fit the head rest covers. Slide the head rest covers over the headrest, pull down firmly and fasten the velcro.
Next fit the double seat back. Open the vertical Velcro seam, pull the seat belt through and then re-make the seam.
Secure the Velcro straps at the bottom around the round horizontal bar found beneath the seat base.
Now fit the seat base covers. Pass the forward most Velcro straps forward of the hinge as shown in the photo and mate the two straps together.
Now make up the other two Velcro straps snugly.
Pull the centre strap firmly and make it up around the cross straps.
Repeat these steps for the second seat base and the job is finished.