Affordable Tow X - 6" U-bolt on jockey wheel - 350kg rated
 
This jockey wheel can be fitted to your trailer draw bar with U-bolts.
Simply pulling the release handle allows the jockey wheel to swivel to a vertical position for quick deployment, or to horizontal for safe storage whilst towing.
Has a 4 bolt swivel mount bracket and 6" solid plastic wheel with a travel distance of 250mm.