Britax Safe-n-sound BS8100A-020133 Series Instructions For Installation & Use page 53

D. Feed the straps through the gated slide to remove any
slack. This has now converted the lap-sash seatbelt so
it will act like a lap only seatbelt.
E. Ensure all slack is removed from the converted lap belt.
NOTE: TO ENSURE CORRECT CONVERSION OF LAP-SASH SEAT BELT TO LAP SEAT BELT
FOLLOW THESE STEPS.
IMPORTANT:

The Gated Slide must be removed from the seat belt if the booster seat and child harness are no longer
used in the car so that other users can use the seat belt as a lap-sash seat belt.
A seat belt extender should not be used if the seat belt is not long enough to secure the child. If a seat
belt extender is used then the buckle must not be in contact with the child.
HOWTOINSTALLCHILDHARNESS
Instructions for Installation & Use - Series No. BS8100A-020133
Hollow side
towards child
Loop on top
Hollow side towards
Lap portion
the child
D
Strap
portion
53