Britax UNITY Instructions For Installation And Use Manual page 24

HOW TO INSTALL
D. Engage the seat belt tongue to
the buckle.
E. Pull the slack out of the seat
belt and ensure the base is held
firm against the seat back. If a
lap-sash seat belt is used then
allow the excess sash belt to
feed back in to the retractor.
To remove the base from the car, release the seat
belt, pull the seat belt out.
NOTE: Seat belt extenders should not be used if the seat
belt is not long enough to secure the child restraint. If
they are used then the buckle must not contact the Belt
Guide Hooks.
If the seat belt will not stay tight in every day use, then fit a 3-bar gated buckle to the
lap-sash belt to prevent loosening. See pages 58 to 59. (Not supplied with seat).
24
Belt Guide Hooks
Pull Sash portion
of seatbelt to
remove slack