Single Ballast Block Base for Goalposts Height Restriction Barriers1 x Ballast Block Base for the new GS6 compliant Guardian Goalposts, the most advanced Height Restriction Barriers in the marketplace. For maximum security, the state of the art, MIRA windspeed tested Ballast Blocks are your best option. Fill the ballast block with water to yield 110kg in block weight for robust stability. In the unlikely case of requiring even more stability; sand, gravel and concrete are viable options for the absolute maximum