Main Material:Carbon Steel. Maximum Door Weight Capacity: 100kg. Suitable for Wood Door Thickness:1.37″-1.57″(35-40mm). Right Choice to Your Door: This barn door hardware kit fits 3-5cm thickness door; Door weight capacity: 100kg. With integrated spring door stops reducing the vibration for quiet closing. Easy to Install: Step by step installation manual with the detailed pictures and concise text makes the installation easier; Time & space saving hardware kit. Notice: Only the hardware is for sale. Just one track to hang double doors, two doors can overlap. About Track: Track width is 4cm, thickness is 6mm; If door thickness is 4cm, the distance from the door to wall about 1cm. About Roller: Carbon steel material with GCR15 bearing, smoother when sliding. Door Stop: 2 PCS. Accoding to rail holes. 1 hole need 1 set. How to choose track size. Track size= 2 × Single Door panel Width. (Like your door width is 3FT, you will need 6FT length Kit).