... open-close test.3.Passed salt and mist for over 72 hours.Widening manganese steel spring,can disperse force when the ... 5mm,Instead of common one thickness 1.5mmAdopt advanced hydraulic system,longer life time,smaller volumeStrengthened spring,buffer hinge,bumper ... Instead of common one thickness: 1.5mm3, Adopt advanced hydraulic system,longer life time,smaller volume4, Furniture hinge Clip-on fitting ...