Allen Bros extreme high load vang block (with key)A new specific vang block featuring a 30mm Extreme High Load Block (XHL) With SA. 873. The block features the same extreme high load dynamic bearing technology as the rest of the Allen XHL range, but has been specifically adapted to work as the Laser dinghys top vang block. The XHL range was conceived when the Allen design team worked with the Worlds top International Moth sailors to create a solution for the extreme high loads they were putting