Ifor Williams HB506 Single Van Trailer . Able to accommodate up to two horses, the Ifor Williams HB506 accommodates horses up to 16,2 hh. In standard, Ifor Williams double trailers are equipped with a large inspection window on the front panel, which allows a better view inside the trailer during transport, while allowing much more daylight into the trailer. A complete central separation system is also a standard feature of the double horse trailer Ifor Williams HB506 . – This can be easily removed, creating a much larger space to transport a single horse alone or be used to transport general cargo.