SAS Fortress A Hitch Lock for Williams TrailersSAS Fortress A Hitch Lock for Williams Trailers The SAS Fortress Hitch Lock Range is a versatile range of high security hitch locks that can be fitted either when unhitched or hitched to your trailer or caravan. The Avonride Head on Ifor Williams Trailers was specially in mind with the design of the the Fortress A hitch lock for Ifor Williams Trailers. The SAS Hitch Lock gives maximum security by completely covers the hitch head and bolts and makes it