SafeCell Impact Protection is a safety system including a steel frame, energy-absorbing base and patented V-shaped tether.nSide Protection, formed by a deep energy-absorbing shell, shields your child from the most severe type of collisionn3 Recline Positions for your childu0026#39;s comfort and safety.nQuick-Adjust 10-Position Harness and 2-Position Buckle allow you to move the harness upward and buckle outward for a comfy, secure fit as your baby growsnEasy-on/off Lower Anchors lock into place with a click and are easily released with the push of a button.nMade to grow with your child, the Britax Marathon G4.1 Convertible Car Seat is a carseat children and parents both love. Made for rear-facing infants 5-40 lbs. and forward facing toddlers, who are at least one-year-old, from 20-65 lbs. The included base features SafeCell technology which is designed to compress is a crash, significantly lowering the center of gravity and counteracting the forward rotation of the seat which is what normally propels a child towards the front seat. SafeCell technology is also present in the carseat and helps to manage crash energy and forward head movement while keeping the chest clip properly installed. Integrated steel bars strengthen the connection of the seat to the vehicle and reduces the forward flexing of your child in a crash. Energy-absorbing versa-tether features a staged-release whether webbing which slows the forward movement, reducing the crash forces reaching your child. It also features a two-point attachment which minimizes forward rotation while anchoring the top of the child seat. Made with energy-absorbing EPP foam to distribute crash forces, the side impact protection has deep side walls lined with EPP foam to distribute crash forces, shield your child from vehicle intrusion, and contains the head, neck, and body. Easily buckle your child in the tangle-free, five-point harness which distributes crash forces across the strongest parts of the body and also provides a secure fit. The quick-adjust harness repositions the harness shoulder height without disassembling the harness straps while the EZ-buckle system and harness holders keeps the harness straps out of the when while you're placing your child in the carseat. It also has a two-buckle position for your growing child. High density comfort foam provides your child with an extra layer of padding for added comfort while the infant positioning pillow is not only comfortable for your baby, but also helps you to achieve a proper harness fit for small infants.