Britax 3 Bar Gated Buckle
If you are not getting the stability you'd like when installing your child restraint, you may benefit from using a gated buckle - or "gated slide buckle".
The gated slide buckle can be used in vehicles with lap sash belts where the tongue slides freely and prevention of seat belt slippage is necessary, or where conversion of a lap sash seat belt to a lap belt configuration is required for use with a child safety harness.
