... 550mm Quadro V6 with silent system/concealed runner/undermount drawer slides/condealed slidesProducts Specifications:Norminal length :250,300,350,400 ... ,up to 6 precision steel ball tracks in the rail,guarantee the incredibly smooth sliding action. 2.Self-cleaning ... integrated in all our concealed ball bearing slide(runner,rail) Saving kitchen manufacturers additional production steps.Silent System is ...