Swivel castors, fixed castors and options for combining them. Swivel castors and fixed castors can be combined in different ways: the most usual way is to affix the swivel castors to the front and the fixed castors to the back. This ensures the trolley is easy to steer and keeps on course. Furniture dollies, in contrast, should be highly manoeuvrable. In this case, using four swivel castors is recommended. Swivel castors are also often equipped with wheel stops or double stops. This ensures the trolley doesn't roll away and remains safely parked. More information can be found in our purchasing guide.