Details Renusol : 900057Renusol 900057 M8 hexagon safety nuts are required for the assembly of FS10 flat roof systems. Each FS10 upright requires 1 x 900054 M8 washer and 1 x 900057 M8 hexagon safety nut. M8 hexagon safety nuts are sold in packs of 100. Key Features: Required for fixing 520001 & 520002 sets to FS10 Concrete Foot