This is the same as our H-RA but with a UHWM (ultra high molecular weight) roller. It's a lot more durable than the standard poly roller. Use two 1/2 " carriage bolts (not included when buying this item individually) to attach this to a plate. This can also be used anywhere you need a roller on a dock. This assembly comes with a standard 6 " UHMW Roller. PDF Drawing