How do I install the Evenflo car seat base using a vehicle seat belt?

Route the vehicle's lap and shoulder belt through the designated belt path on the base, then buckle the seat belt. Press down firmly on the base while pulling the shoulder portion of the seat belt to remove all slack and engage any locking mechanisms according to your vehicle's manual. The base should not move more than 1 inch side-to-side or front-to-back, and the level line indicator must be correct.