This set of high performance V-groove wheels is designed for sliding doors, rolling doors and industrial machinery and provides a strong load carrying capacity of 660 lbs. Each set contains 4 wheels and brackets that can be easily installed on inverted rails, wire rope rails or other relevant locations. These rigorously designed wheels provide stable support for safe, smooth operation. All in all, this set of V-groove wheels is ideal for sliding doors, rolling doors and industrial machines to suit your every need