As several customers have noted this is a replica of the Ronthor Reiss rail that was likely supplied with your furniture. Above the "C" shaped groove at the bottom of this rail is an open slot to accept the rear end of a wooden rail attached to the bottom of the crate. This helps align this lead with the track. The only complaint is that the included fasteners are 3/4" long, which is probably longer than you need and may protrude through the back of your drawer. I bought some 3/8" screws from my local hardware store to use. I bought mine from Grandy's online as the unit price was lower so I could carry a few extras just in case.