National Hardware N112-102 5005 Zinc Box Rail Hangers - Heavy Duty Shelf Brackets for Garage Storage, Closet Organizers & DIY Home Improvement Projects

I'm not sure if the description of the product is clear but it comes in packs of 2 (I ended up with 2x what I needed...but returns are easy with Amazon!). The trolleys work great with the Stanley box track. If you are doing interior doors (like I did) you'll want to make sure you are using 1-3/8" thick doors minimum but it'd be much easier with 1-3/4" thick doors. The top of the trolley is set up for a thicker door and the hole you need to drill in the top of the door for the adjustment bolt is quite close to the face of the door in a 1-3/8" thick door. I believe a thicker door would also hang more plumb. Our doors as solid alder and heavy but still hang a tiny bit out of plumb with these trolleys. After putting a door guide at the bottom on the wall though the doors slid great and stayed plumb. The doors slide nice with these trolleys but remember that these are "agricultural" products and not designed specifically for interior use. The bearings to make a little noise when they slide so if you want a silent sliding door this is NOT the setup for you. But you can't beat the price of putting together a barn door with the Stanley family of products! I'll attach a photo of the setup I just installed with these.