Graco Contender Slim Instruction Manual page 39

10. Tighten the Lower Anchor Strap
Press down firmly in the center of the car seat while
tightening the lower anchor strap.
Note: You may need to tighten through the rear-facing belt
path to get a tight fit. To expose the belt path, unsnap the
bottom cover on each side and pull the seat pad forward
out of the way.
11. Test For Tightness
Grab the sides of the seat where the lower anchor strap is
and slide the car seat side-to-side and front-to-back.
If the seat moves less than 1 inch (2.5 cm), it is tight
enough.
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