The bottom section of the VIP is designed to straddle the center guide rail that is most often found in the channel on the floor. (This is the groove that the your sliding door follows).
The VIP will fit center guide rails that are 3/4" wide or less. The VIP will fit 99% of the tracks out on the market, but you will want to make sure that the center guide rail is not wider than 3/4".
The overall thickness of the VIP unit is 1 1/2" in width. These will closely match the thickness of the frame on your sliding door. The VIP is equipped with hardware allowing you to LOCK your slider to the VIP, (99% of the time). Otherwise a brace-bar is recommend.