This product is sold as a pair and is enough to do a single door.  We recommend 3 (1-1/2 Pairs) slides for extra heavy doors and above 32 in. in height. If you are doing two heavy door just get three (pairs) of slides as the slides themselves are non handed

 A very smooth running slide system with 6 ball bearings per inch length of the retainer.

 Follower (Sold Separately but required) is made of 2 mm thick steel and is very rigid without deflection 

 Any hinge manufactures hinges and base plates will fit and are attached with sheet metal screws to the follower. However baseplate thickness and overlay are critical to make it actually work. We have provided Salice Hinge and Baseplates as part of a proven solution that will work if installed correctly.