Safecell impact protection is an integrated system of safety components, including an impact absorbing base, tether and harness, an impact stabilizing steel frame, and complete side impact protection plusnSafeCell complete side impact protection plus provides an advanced level of protection: a deep, foam-lined shell absorbs crash forces and shields your child from debris, and an energy-absorbing headrest keeps your childu0026#39;s head and neck securenClick and safe snug harness indicator gives an audible click to aid you in the proper tightening of your childu0026#39;s harnessnDesigned with comfort and safety in mind, the Britax Boulevard G4.1 Convertible Car Seat features a bevy of safety features that will help give you peace of mind. Made for rear-facing infants 5-50 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 true side impact protection offers a head restraint which creates an extra layer of EPP foam, keeping your child's head, neck, and spine aligned. Deep side walls, also lined with EPP foam, shields 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.